THE UNIVERSITY OF ILLINOIS LIBRARY / 92 S N 76 UNIVERSITY OF ILLINOIS ___JIAZ_2.5 i922__. THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY L MQ2EER _ LdlUlZilEUIER . ENTITLED ^--STIII)Y_Oi!_^UlLniE-TK_OjTIS._AlIIL_aEAHaOAL. IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF BAGHSLQH..CL5_^GLSl!lGE : -r O V S y/W i' 4 i Digitized by the Internet Archive in 2015 https://archive.org/details/studyofsulfurincOOmont This work was undertaken at the suggestion of Dr* li!. J. Bradley and carried out under his direction. The 7/riter wishes to take this opportunity to ex- press his appreciation and thankfulness to Dr* Bradley for his guidance, suggestions, and helpful criticisms, and to B.W, Weeterman and F.3* Yanderveer for their help in the experimental work of this investigation. TABLE OF COUTEiTTS Page I. Introduction 1 II. Literature 7 A. Bulphur in Coal 7 B. Clianges in the sulphur Combinations 8 During the Coking Process. C. Sulphur in Coke 10 D. Possible Character of Sulphur Compounds in Coke and Charcoal. 14 III. Experimental 18 A. Description of Apparatus is 3. Method of Operation 19 C. Method of Analyzing Products ly D. Preliminary Work 20 E. Series of Experiments Using CSg 22 F. Series of Experiments Using EgS 26 Go Series of Experiments Using Eg 29 H. Removal of Sulphur by Steam and Water Gas 50 I, Removal of sulphur by Miscellaneous Gases 32 IV. summary 34 V. Bibliography 36 - 1 - A Study of sulphur in Coke and Charcoal I. Introduction A. It is the purpose of the investigation to study the forms of sulphur in coke and charcoal and their reactions at different temperatures toward various vapors and gases to give additional information which may apply to the removal of sulphur from metallurgical coke and gas, Wood charcoal, and petro- leum, metallurgical, and low- temperature coke were heated at various temperatures and subjected to EgS and CSg vapors. Surface and interior samples were taken of the resulting carbon substances. This impregnated coke or charcoal was then returm- ed to the furnace for further treatment to determine the effect of various gases, as hydrogen, superheated steam, water gas, xylene, and illuminating gas in removing the sulphur from the coke and charcoal. All outgoing gases were analyzed before burning. B. Sulphur has always been an unwelcome constituent of coke and gas and as the supply of low sulphur coal constantly decreases th^resence of more and more sulphur in these becomes a problem of great industrial importance. This high sulphur coke, when used in making iron and steel, produces a poor grade of metal, making it brittle^ and more easily attacked by acids^* As a fuel, not only does sulphur lower the heating value, but also increases the difficulties of operating the boilers and and disposing of waste products, and causes corrosion of metal parts such as valves, boilers and chimneys, and even concrete structures^* In gas it produces unpleasant fumes, corrodes chimneys and metal parts of lamps, burners, roofs, guy ropes, etc. Gas purification has also now become a problem of consid- erable importance from a chemical and industrial point of view. The use of gas in chemical industries has recently been devel- oped. The generation of hydrogen for the requirements of cat- alytic hydrogenation processes calls for the purification of enormous volumes of water gas* This reqtlAres au extremely oare- ■ ®liniination of all sulphur compounds, as otherwise the mach- inery would soon be ruined, the steel would soon deteriorate in strength, and the catalysts be poisoned^^ Again, the sulphur in producer gas is a big disadvantage to steel manufacturers since open hearth steel is contaminated by this element^. The above enumeration of some of the most deleterious effects of sulphur in coke and gases, along with the fact that every day our supply of coals of low total sulphur, the most im- portant factor affecting the sulphur content of the coke and gas, are rapidly diminishing, indicate the importance and necessity of directing more and more attention to this problem. C. All the known processes used to produce a low sulphur coke may be divided into three classes: (1) Those processes in which an attempt is made to re- move the sulphur from the coal before coking. (2) Those processes which involve the elimination of -3- the sulphur as volatile compounds or its conversion into such compounds at the temperature of the coking process, which may later be leached out with water, (3) Those processes in which the sulphur of the finished g coke is attacked to secure its removal Under the first method we have attempts to eliminate the sulphur from the coal by washing it. The success of this meth- od depends upon the form in which the sulphur occurrs, and upon the efficiency of the washer . This treatment removes a part of the sulphur which is combined as pyrites, but affects neither the finely disseminated iron pyrites nor the sulphur in organic 7 combination o In most cases one fourth to one half of the sul- phur of the coal can be removed bj?- washing, which means a cor- 8 Q responding reduction in the coke sulphur . J.E. Campbell ad- vocates the sink and float method for washing coals, which he says will reduce the sulphur content E6-40fb# The second method is probably by far the most common one for it is more convenient to apply a desulphurization process during the carbonization period than to the finished coke. F. Wuest and P. Wolff^® state that the practice of coking coals owed its origin not so much to the desire of obtaining a non- flaming fuel as to the idea that the all important object to be obtained was the desulphurization of the coal, A successful process must of necessity be cheap, and m.ust remove a large percentage of sulphur, and must not affect the quality or quan- tity of the coke produced. Among the methods of this group we have the processes involving the passage of gases through the -4- ooking mass, A. Soheerer^^ claimed a loss of|o.4f!. sulphur was produced by passing high pressure steam through the oven before drawing the coke, A patent of Claridge and Boper in 1858 invol- ves the same process. Woltereck combined air and steam at not over 400 °C. The sulphur was driven out as SOg but excessive amounts of coke were used to obtain the desulphurization. Wuest and Wolff^^ in experimenting on the passage of various gases over powdered coke removed by steam 12.84ft' of the sulphur of the coke at 500^0 , 36. 8&^ at 800^0 , and 54.34ft at lOOOOc. From the excess- ive loss of coke by ignition as compared to the desulphurization produced, they concluded that such a procedure was not practicable. With nitrogen they found that 2,41ft of the sulphur of the coal was removed at 500°C, 6.97ft at 900°C, and 17.35ft at lOOOOc. With COg 6.47ft v/as volatilised at 500®C increasing to 59.24^ at lOOOOc, but a very great ignition of the coke resulted. They assumed the reaction 200£ + 8*^ 200 *f SOg to take place, the burning of the sulphur to sOg depending on the reduction of COg at high tempera- tures by contact with carbon. Phillipart^^ eliminated part of the sulphur in coke as 20g by passing air through the coking mass, but only at the expense of large quantities of coke. There are two processes involving the use of chlorine gas. E.L. Stonerl3 treat- ed the coke in the retort at the end of the coking operation with hot chlorine or chlorinated gases, and then washed to remove soluble salts. The process is expensive and tends to destroy the character of the coke, and its byproducts. Fingerland, Indra, and Ilesnerl^ claimed to produce a low sulphur coke by distrib- uting catalysts as metals, or the hydroxides, oxides, or salts I J . . 1 ■ ( V, t ' ■ ■ ' )' r > 'l , ... \ • . I ■ ‘ f • •, 'I ■ ,1 •- ' ■ U.i, ) 1. . ■ ; 1 '; .if I r , iju , r ■ ■ !•’. r" - . X c •.c ■ , . .f. , i. of iron in the coke "before coking, and during cr-rhonization passing chlorine vapor through the hot coke, The^ held that the resulting compounds, Fe^clg and SClg, volatilized in the current of chlorine so that the ash content of the coke vas not increased. They also claimed that at the same time portions of the hydrogen contained in the coke escaped as HCl, enriching the residue in carbon. The excess chlorine was removed by bloving steam, hydro- gen, or gases containing hydrogen through the incandescent coke. Severe! patents on the use of 00 in desulphurizing have been re- corded but they give no data as to their efficiency.^ Wuest and TTolff however, found 12*8f^ of the sulphur of the coal or coke removed at 500°C by CO, the percentage increasing to at lOOO^C with a comparatively low ignition loss. They considered the reaction to be S f SCO “ 2C SOg. ?/ith hydrogen they found 7*59^ volatilized to H£S at 6C0°C increasing to 22,09f^ at 600°C and 51. 17^ at 1000°C; extending the time of treatment in every osse increased the removal, since they were unable to ascertain the exact nature of the organic sulphur present in the coke, they explained the results from the reaction FeS + 2E “ 2Fe <► H^S. A.B. Powell® oonduoted experinents to stud- the removal of sul- phur hy using hydrogen gas, either pure or as contained in hy- produot gas. Pure hydrogen was first passed thjrough a small Ish- oratory apparatus at the end of the coking operation, at the rate of lOOoo per minute at the temperatures up to lOCOOc. The entire desulphurization effect of the hydrogen was found to be due to the increased conversion of the organic sulphur to H s. _elow 600 C the elimination of the sulphur due to the hydrogen" - 6 - is very slight hut above 500 °C it is increased enormously, as high as 90fo in a Freeport coal studied, showing that desulphur- ization in this coal is most active at the higher temperatures of the coking process. Powell further states that a secondary reaction, due to a mass action effect, fixes the sulphide sul- phur in some combination with the carbon of the coke, the hydro- gen causing an increased decomposition of the pyrite up to 500°C and the constant elimination of the organic sulphur above that temperature as HgS. A bOfc mixture of hydrogen, as in by product gas, produced much slower desulphurization, but caused a decided removal of the sulphur. There are also those processes involving the addition of compounds before coking. In the Calvert^^ process in England salt is added v/hich is said to give good results by forming, dur- ing the coking period, volatile compounds of sulphur. It has never been applied on a commercial scale however. Franck^^ has a patent process involving the addition of hnOg which he claims liberates oxygen and effects a rapid combustion of the organic sulphur compounds. The quenching operation may be considered a process of desulphurif«ation of the third class in which the removal of the sulphur of the finished coke is attempted. J.B. Campbell^^ states that the action of the water in quenching reacts on the iron sulphide of the coke, as follows; FeS 4* E2O = FeO + H£S. Experiments, however, show that only an infinitesimal percentage of sulphur is evolved during the process. It is stated that the addition of ECl to the water will greatly facilitate the removal of the sulphur. Eoffinan^^ states that the addition of an acid -7- solution of manganic and calcinm chlorides to coke removes sul- phur as EoS. As has "been already stated it is more convenient to apply the necessary desulphurization process during the car- bonization period than before or afterward. As Powell^ states, " if in some way one might affect the sulpur reactions of the coking process so as to secure larger amounts of the volatile sulphur compounds and less of the residual, the problem would be greatly simplified”. It is quite possible that the lean gases, byproducts of the carbonization of coal, might be utilized for the desulphurization; such a process would not injure the coke and not materially affect the byproduct gas itself. A successful application of this however requires an exten- sive knowledge of the reactions which the sulphur undergoes during the coking and the nature of its combination and occurrence in the coke. II. Literature A. It is now quite generally conceded that sulphur occurs in coals in an inorganic form, mixed mechanically with the coal, and as resinic and humic constituents in organic form^®. Pyrite is generally found in coal as well as marcasite and magnetic pyrite, Fe^Sg. Other inorganic compounds also occur rarely, as in sul- phates, but the amount ie generally small . It was formerly be- lieved that all the sulphur in coal was present as pyrite, FeS£, but this is now known not to be true. 20 In 1843 Berzelius apparently made first mention of a solid organic compound of sulphur in coal when he stated, ”Lie Kohle v smo i VW ^ 'Wi •;: 'v-'t',.- c.f Iv j ■ I tfi jt. -^'J- ,( .V. ^ fci ' £ Jw ■! * • * V* lJ 3 •> ,v. . .1 fi .:. i (n & » >■ ' '.■• ■ 'ji •‘>.rXv>v/ds, Vx;.v;x.->.r^ '. V.0 .r'fi- '/’i.ri'J: X-cl'rofr no i J“; .lixu, U fr-tj . "\ /.■ ^ ^ ,■.■■•■ .• ■■ . ■ .■: . ,; ,. /^, ,,. *,• JV r, • • ; ' ,LC ; •=. i.-jv-i '■ '•■:;.V^.- ,: : s o'»: c-t'j'-'f -•-t >.l n u,:. :•:■ :’•'■• *4Q. yK- , V ;: -.f ..' • !• ) -yfilo.Kr f)Ii£ bC’.IIf ' .- 'CO ■..•if„’i tXi/y » /‘O j. 4 , .jbsv . - ■ i,-- ' ' ■ ' ' • ■ ■ " '.. ’■% JTi, ' ' V>- ! n •* ! '. : :fc:'.. ''.i.u\ ,;. ;• A fo.V': ; * f .' ^ - ,....:,jii . ■ , ■■■ ' ■ • - .. . ‘’ . •■> ■ ^ ■■ ■■ • » -fo ; . r-1 n.rxi., "lo ;rf i ; X ,t ,M, rxn>oi::v -•j.'.i.- i.:; , :>.:■ .iyi i .ro.,o''-. >4,^ ^0 rr,i nontn-.i;:’’ j.^ ii.. ' r.v j .**. ; iibi'.xc- ;u one;,’ .}\,:J f X L'.tl' 0'f.iu •>•■.,■ ■• ,rv •> . e^,-,.i,- «.»H V i '■;-i:;j. i.n'oJ'.LT * •J :'f. uoc xy..\ i'^.o j ■.: ft jLiO 0 V f I <:i.tiv; . .’Oit -)i -u ^fT , .•>,•:) rUl’-- ::^u. .; : .-•’^.t* OOK , ■. :i0l !,)Ifr4;;'£L,(£i; f.fj 'lil 1 >JU ■ • ■ •:;■£•.. .o.>;rc 1 ./o.'.'..'ii‘.>£(oai ci'-iw. ■ ■):• i ::Ii r: ’ ,■■ ■ — -.p: vx i:*r; rj.o’,v X vC .v ni " '-J i rt nuVo ,i 1' inp./o ‘ ; .!.»•; bia^^’ce, / ^'X.i:, Vv' jfrtOl?:r .'OX; ^ ' : • -•■,•«: ; .••!-«v X;tct) .;*i *s;.f 'tlriy oV*X .LI ' r •■oT ' d97f>il ■'v : -'n ';X tT Tc.x.nv'ort:' VO ^ i . .tow doc/ r • •<’ I ’.i; [r 'zc :. v li^'-'r oj;';. >..'i . -j' ,*‘‘X‘rx.^‘i''pf'; ‘ i-XSI .'.I. ' f>I 'To:, oi,,.‘ , ,‘ -■ T e ' o : xij\:i i;cj; ni, 'c^.:-:X£;u T;x Uisjc(j^yjD cii-ne^'cc T V Ti «rdf.iBh . ,1 . ^ ' ■.. , V» «*,'• oi'T/AT' -t/.A'iii, ■, rasr - 8 - enthSlt Scliwefel in chemischer Verbindting der nicht dnrch Glllhen ausgetrieben warden kann, wenn dabei der Zutritt der luft verhin- dert wird’’. Professor J.G. Wormley^^ (1673) called attention to the fact that many coals containing little iron, have a larger percentage of sulphur than can be accounted for if the sulphur were combined only with the iron found in the coal. His experiments go to prove that a large part of the sulphur found in coals exists as some organic compound, the exact nature of which he was unable to determine, A,S, M'Creath^S drew the same conclusion, reasoning from the excess of sulphur required to convert the iron into iron pyrite, Himball^S reviewed the whole field of sulphur in coal and concluded that some of it may be combined with organic matter, the same as it is supposed to be combined with rubber in vulcanized rubber, Prown^^ observed figures from his analyses which lead him to believe that sulphur must exist to a great extent in coal as organic sulphur, Wuest and TTolfflO point out from the analyses of Muok^*"and 3 lum 26 that percentages of organic sulphur in coal, ex- pressed in percentages of the total sulphur content, vary from 66-r92f4, Wheeler showed by extracting coals with CHCI -7 and that organic sulphur is present. Thiessen^*^ from a micro- soopio examination of coal in thin sections, states that a certain amount of sulphur is found, to be present in an amicroscopic form probably to be recognized as organic sulphur. 3. When coal is subjected to destructive distillation in the absence of air the sulphur divides between the residue and the vol- atile matter. The phenomena taking place during this transforms- tion of coal to coke is quite complicated and it is difficult to -9- determine in what relation the sulphur of the coal is divided be- tween the organic and inorganic conipounde end whether the sulphur as PeSr, or in the organic form is the more volatile, Drovm®8 found that in coals containing a considerable amount of sulphur both as metallic sulphide e,nd as e,n inherent constituent of the coal, and at the same time low in volatile matter, the elimination of the sulphur during the coking, appeared to be limited to a portion of that existing as pyrites, the organic sulphur not be- ing affected, by the process. In other coals, lowr in pyrites, and low'er in volatile matters there was an elimination of organic sulxh.ur to the extent of 25-45f:. Widely divergent results and many different theories have been advanced to explain the reac- 20J tions undergone by the coal sulphur during this change. McCallum concluded that a somewhat greater percentage of the organic sul- phur than of the^rganic was volatilized. J.S. Campbell^^ states that most of the coal sulphur is pyritic, thtt 42^"' of this is volatilized during the coking process, the rest remaining in the coke as pyrrhotite and that most of the organic sulphur is re- tained in the coke. .erofessor S.V7. x-arr^^ states tha.t in the coking process, the organic sulphur in the coal is broken down, part of it remaining in the tar oils as thiophenes, end part going with the fixed gases as IlgS, and half of the sulphur of the FeSg is discharged for the most part below 500°C» As 700°C is approach - ed the final sulphur of FeS is discharged leaving, metallic iron and a carbon suphur compound. Powell in a lengthy discussion of the reactions taking place during the carbonization period states that a decomposition of the pyrite occurs at 300°C, is complete at 600°C, and reaches its maximum between 400g500*^C* - 10 - Also that it may be assumed that any sulphates present v/ill he reduced to the suj)hide. In the presence of a large excess of the coal substance the decomposition of the pyrite produces FeS and A large part of the former is further decomposed, the sulphur apparently entering into combination with the carbon. The evidence for this is simply the fact that during .the later- stages of the coking process there is quite a decided increase in the sulphur held in the carbon- sulphur combination, with a decrease in the amount of sulphides present. He also states that the organic sulphur of the coal persists almost unchanged in type up to 400^0 . From 400^0 to £00°C a decided change in its charscter takes place but the resultant carbon- sulphur combination has all the properties of the sulphur, existing in this form in t he finished coke. Secondary reactions also play an extremely important part in the coking process, those between the organic sulphur compound and the hydrogen of the gas to form HgS and the red hot coke to form CSg being typical. The fact that the latter substance is not a primary product of coal dis- tillation has long been known. C. After tracing the changes which the sulphur of the coal undergoes during the coking process, we naturally find ourselves asking as to the nature of this sulphur retained in the coke This has always been a problem difficult to solve. Powell^ states that it consists of iron sulphide either as FeSg or pyr- rhotite along with a larger quantity of a very stable organic substance. This latter form is not affected by either HCl or HllOg and is extremely stable to the action of oxidizing agents ■‘ * .■'. ' I,'* . i. ■'■■' “V- oc. •'■ M. S'.' •• • r A r.,M .s V ■ '.i" ■w: r, c • i..,- , 'I ^r. ■ I n". . ..^' Ct;': ■■< :} r o5;fc r fu ’ .,4t.:t«. i'.vU*" *•' - I' ■ it ■ft \ ■ Un '.>1 ;i '4V "■ -o; >;U7 t).\^ . •'>/ Vf -'■' •> , < '■': '.I. ■ i ••■ • , ,*■: K; . ^ r ’ ; .‘.' i' t.' I'i r jV; ‘ " T»v T,' I' .'1 ' *■ ^ ■'• 1 • • *L' t*'' f , •:• . \i. I . ■' r K /i) . I . . n. 1.:.: : r ;....) c- ttw oe’fi' oA'^' •* ,1 > v,vt?*Ayo» . ;< 3 ;,r .;,^:yrr ! ' ‘ : : »: ^ r.r %:: rik. c-ir. /to- uJi^ f : tJ .a-t .'■^00> cX i/ ^ i '^u/v-Ui . _ : ;.. 0 V:: • -.t »vr* 't v . ;u* i li ■: /’■/ ■'.'. •. i)X : 'Vy t '■• ■ 'I * f.-'. '■i'A'C'-l.f ■ o ' j i- -’7vr):j ••. ?--•/ •> ;. *• '••■•.. . r JT, SJit'if '' 1/- ’> . )'C /T- . i:;; y ■'< : :.':i':7. 0 O.l . r' : ;• 'C /i . ^ , t Ciy r V ' y . 'j i » f’l c>5;C f’ J. "t^lcai i 1: •/■ . Lrfl '.- ivl ' V 4 » jr ^ 1 . V .; ^ 4 w ' X tX'f> fir ■■' ■ >4i ' b':^‘o.;•::• r i. .. f t; > 4 ■' »k:.:/:,\.i:'J -.f/i.'ru 7. C;»’ .;-/J '■ ' 0 ;> k .ri: V,ri7/ -y; 1:0 vri;;/rny. t '■'/ -■ •< - . ■ Cl' ui‘- < ' ' ■ ' ^ ,. ■• '/'■'■ • ' ' ■ , ' ' _ ■ ^0 .:■ if 7., rcTi.kr '3 /; ■ ci.fioc ••■»d'y,4 7 ^ r^ .. r f. yxq '.)Iu .f; /■ '.. , j| _ t ? ... »' -L^vU -'1- U ^y-.. 11 - and heat at 1000*^0, but is readily discharged from combination by the action of nsscent hydrogen^^. V/.A. Bradbiiry^^ as early as 1878 states that the data of Percy^^ gives analytical evi- dence to support the statement that sulphur is presnt in coke in some organic combination, and may be considerably more than intthe form of sulphide. Truest and Wolff^^ found the propor- tion of organic sulphur in coal as 8d*2^ of the total sulphur present. Just what is the form of this organic sulphur compound of coke? Solid compounds of carbon and sulphur formulated as CS, C2S3, and 0285 have been described but these are either gaseous, liquid or if solid have melting points far below the temperature of coking • Since it seemed impossible to isolate the compound from coke many investigators have applied a syn- thetic method of attack in an endeavor to throw more light on the problem. In 1865 John. Hunter^"^ experimented v/ith the pas- sage of CS2 over cocoanut charcoal, and obtained the following data: (1) 117.7 vol. of CS2 absorbed at 100°C at pressures varying from 671.0 to 671.2 mm. (2) 91.2 vol. of CSg absorbed at 167.1 to 168. 4°C at pressures varying from 658.1 to 658.6mm. (3) 81.7 vol. of OS2 absorbed at 101.7O to 191.3°C at pressures varying ffom 690*3 to 564.4 mm. (4) 88.5 vol. of CS2 absorbed at 160*3 to 162*8°C at pressures varying from 697.9 to 679.0 mm, from a, mixture of lOcc of CSg and 20cc of alcohol. Calculating this to the percent sulphur found in the charcoal we find 17.75^ retained in (1), 12*45f^ in (2), 11.19^ - 12 - in (3) and 12.59f^ in (4). It is to le noted that with the ex- ception of (4), decreasing amomits of sulphur are retained v^'ith increasing temperatures. W.G. Mixter^^ (1693) found that when sulphur vapor was passed over soft sugar carhon, and the latter then cooled and dried with a stream of hydrogen, the carbon was found to have retained|l9.97f^' sulphur. Y/hen subjected to the heat of the combustion furnace, it gave off a little KgS but no CS? , and when heated in s Perrot furnace at a temperature suf- ficient to melt cast iron readily, the carbon still retained 3.4^ of sulphur. However when the sugar carbon v;as first heated to the highest temperature of the combustion furnace to drive out all occluded gases and then subjected to sulphur vapor for twenty minutes and cooled and dried with hydrogen, no sulphur combined. When GS^ was passed over the charcoal at a red heat and exposed to the sulphur vapors, and then cooled as in the other experi- ments 11*14^ of sulphur was retained. Filter paper charred at a dull red heat, and exposed to sulphur vapors showed a retention of 29*1^ S. Loose rolls of filter paper soaked with a saturated solution of S in 0S£, gradually heated to incipient redness, dried and cooled with hydrogen, retained about 46 sulphur. This resulting charcoal yielded nothing to boiling CSg and gave up no sulphur to a boiling HOE solution. He concluded that his results show that nearly pure amorphous carbon takes up little sulphur, while a soft charcoal, containing hydrogen and oxj.’-gen, takes up considerable sulphur from and forms a chemically combined compound not removed by solvents even when it contains nearly 50f^ of sulphur, but is entirely removed by hydrogen under proper control. Wibaut and Stoffel ^^,h€afAn^ sugar -13 carlaon or wood charcoal mixed with sulphur, in a closed crucible to a bright red incandescence obtained products which after ex- traction with OSg and then ether, contained sulphur to the ex- tent of 3-6f!', They were unable to decide, hov/ever, whether it was chemically combined or only absorbed. Jeude in study- ing compounds of sulphur with carbon, stable at high temperatures drew the follov/ing conclusions from his work: fl) Carbon seems to have an avidity for sulphur at high temperatures. (2) A certain percentage of the sulphur is combined with the carbon in such a v;ay as to resist the action of solvents on heating in a current of inert gas as distinct from the excess sulphur which is removed by the treatment. f3) The amount of the sulphur taken up by the carbon seems to depend on the refluxing temperature, less sulphur being absorbed at the higher temperatures. (4) The loss of sulphur when heated in a stream of nitro- gen, seems to increase with increase of temperature. (6) Cokes made at high temperature are relatively stable at low temperature when heated in a stream of nitrogen. O.C. Russell , from his work on sulphur in coke, under the direction of Professor Parr , concluded: (1) In the study of absorption of sulphur by carbon, the determination of volume change of HgS in passing over heated carbon, cannot be used. (2) The sulphur of KgR is ehsorhed by oe.rbon In increas- ing amounts up to a temperature of 700° to 800°C, but above this temperature little is effected , the infereno e being that ./’H, ’ , ; ‘ . 1 . V • : V’ ..V '"v • r t'- *■ If '1 ,:.~0 Xt' -j'i - . .! , ■ r'f£>X‘-' i.r J'fCs ^ - A - \ * *1 'X*; : ;,C;! ^ . ' .”v ',l'> '-■’ .u U sJ f: iJ"‘ ‘ . 0 7 ‘i..( .t.- 'i jXf i . , ■Of. Si j’«' ii; ■ ■'V'- ■■.'iOO:, \.lac 'to I!'' , i. J ^ V .’w 4^ :J-:. 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'''ira ' / rr.-j ;t'. ‘-t I '-'yjjJri .«’» .i X (v.*' xi^vc ■ ra«-.j ■•••^ xc ot^iXrTfiv c :' / L'X' i’ O.Oi ‘ 'V ' iu ■ . , ' . r , , ■ '>xv'c;.x ' xo -.acr:;:-' ■' :'.X <"X " ■ ' ' ■ <,,r> I , ■ . ■ ••' > .-■'■* tyotf'M «Ji .'^Xv* i^XX-' !'=:prt=r«=rfer.'“: iw yMyi wri ‘irlfY ii lyi . > tot>: ..c ...c.Lloc'iX- »a>< 'f{,' .» * T. jk -14- hydrogen formed by dissociation of the HgS begins a purging action at this point. fS) Coke carbon begins to absorb sulphur above 450^0. f4) FeS£ mixed ?/ith sugar carbon and heated to 750°C is converted into a magnetic sulphide which in turn is partially reduced to metallic iron. (5) Carbon absorbs some of the sulphur which is liberated from the FeS to the magnetic sulphide. D. I • We now arrive at the work of E.M. Chiles who in his studies of the nature of nitrogen compounds in coke, was apparent- ly the first to call attention to the possible explanation of the form in which nitrogen and sulphur occur in coke by Langmuir's theory of surface compounds^^. According to this tbieory^f we consider s particle of pure carbon, each atom of this particle is chemically combined to all the adjacent atoms, v/hile these in ; turn are combined to those beyond. The arrangement of the atoms in general does not follow the usual rules of valence, but each atom is combined with a much larger number of atoms than cor- responds to its normal valence. Thus the valences on the inter- j ior carbon atoms may be considered to be completely saturated but the surface layer of the carbon atoms should be unsaturated and quite reactive, combining with atoms of other elements much ^ more freely than can the atoms of the interior. The surface must be looked upon as a sort of a checkerboard containing a definite numoer of atoms of definite kinds arranged in a plane lattice formation. The space between and immediately abovefsway from the interiorHhese atoms is surrounded by a field of electromotive -15- force, more intense then that "between the atoms inside. When a molecule strikes against the solid surface it may "be reflected, that is, rebound elastically, or it may condense on the surface, that is, it may "be held "by the attractive forces in such a way , that it forms, at least temporarily, a part of the solid body. If any molecules impinging upon the surface are condensed a cer- tain time interval must elapse before they can evaporate. This time lag will bring about the accumulation of molecules in the surface layer end may thus be looked upon as the cause of ad- sorption. Much experimental evidence seems to show that this is a truly chemical phenomenon. Chiles states that in the cok- ing process we have the phenomenon of decomposition of compounds of the original coal with the production of carbon and the fur- ther decomposition, in contact with the carbon, of the hydro- carbons, sulphur compound, nitrogen compounds, etc*, probably with the production of elementary hydrogen, sulphur, nitrogen, etc. One might assume that the original carbon particles would become saturated with the elements produced in the atomic state in contact with the carbon. To get a clearer idea of the carbon- sulphur combination it may be best to first describe a similar compound of oxygen with carbon of which much is already known, and then point out the resemblance of the corresponding sulphur- carbon compound. It is to be noted that sulphur appears imraediately below oxygen in the periodic table and has many properties similar to oxygen, different only in degree and not in kind. 41 In 1905, E.E. Armstrong observed results causing him to conclude that the simple oxides of carbon, CO and COg, were ob- 01 ©ni-as anQ. ht sq.o^3 Jn-ctdins aiq-cssodmi q.B q.ou si q.i q.uara^ITj aqq. jo i?poq Jiai^ei naSi?xo 0 0 0 raainrajoj aqq. oq. SxxxpjioooB sq.ueraBiTj: aqq. jo ifpoq eqq Suiiiijoj STnoq.ii xioqjci30 aqq. oq saouax'SA AjieinTjd qqx-A patziqraoo ^xx'tjoxniaqo sraoq.« naSiCxo 3.0 sqsxsnoo q.i ‘panuicj sx uaSifxo paqxosp^ jo mipj aiqsq.3 Axsa ^ q.8qq. tiaS^xo tzx sq.uaaieiTj xcoqjHO qqxis/i sqnampjiadxa 3xq iJq eAOJd oq shixbxo •X'eoojCBqo aqq ^0 qqSxaM X'STQ-Tnx ^g^*2 oq ^XA*I raojj saxdtn'as o/Aq nx pexj-BA X'Qoojcaqo qqxM pauqqnioo ao^ oq pimoj snqq ne3i?xo jo qiniome aqx •iroq.ji^o jo anpx 39 j: -8 SnxABax ^xcfeiimsaxd pixe OO ^OG SxcxaxS iix^ops xi/Aop X8aa:q naqq sapxxo asaqq q^qq Moqs aq^p jcxaqx 'paqo^aj: sx OqOOS JO > JTi q-ej a dmaq -e XTO-tm acyp^ Siixq^q qou sxqq ‘noxqxsodmooap jc aq^j /Aox i?o:aA 8 aA8q qsaap q8 j:o saj-nq^jcadinaq /^ 73 xrxpjc q8 axq-sqs aq i sapxxo asaqx *qu:8qsxioo ^XTJ^'^ssaoen qoTi sq oq tioqx 80 jo );q8j: aqq qoxqM nx qnq ‘sqnaqnoo uaS^c nx ;aox pun noqjso nx qSxq iqjgo JO 0apxxo pxpos ‘ajojanaqq ‘aq pxnoM ifaqj; •spnnodraoo eo8j ia S8 X'^oo-ieqo aqq i?q ppaq sx naSiCxo n'gsxrjii sxqq qsqq pns ‘noxq ijosqn /q nsqq naqqo x^oojnqo ifquPaxxj,* aq u-&o naSiCxo qsqq aptipo *y*G pti8 *II*H 'qnasojcl xapdiuoo jo qnnomn aqq ssax aqq ajnqsnadniaq aqq jcaqSqq aqq q^qq aqsoqpnx' sqxxisajc jcxaqj; /> •lO pns oQ^ oqnx qsaq ^?q pesodTnooap sx qoxqA; noxqxsodmoo axqBXJCSA X i JO 0 0 xaxdnioo uIBOxuiaqo-coxsiCqcI*,8 rajoj oq ^x4-Ooj:tp noqjno jo jsnm 8 qqxM sanqqnioo naSko qaqq noxsxixonoo aqq oq pnax iapaaqjii pnn pnaqq jo saqojcgasaa naqsp eqi ‘xapdraDO naSi^xo -ncqjso pa ipqxo i^xo^oi^Iraoo ssax JO ajcoin 8 jo xcMopq8aj[q aqq ^q ^x^o panxsq - 91 - ! ) ■ ; f- ■..h S " >J - ■ . I" '■ f • •C- J, • V > •■■■ I :• O-y.j-’T-' ’•'*'• • .V .'V-V';! i. V V ; ' I ' . ( . 1 •■jV ".J ■ I I » ■ c- -fri’' , ! / ■ '. \ '■/ ■ ' ’ ; 1 .' * J'_l, ! • ' / ■ ''' f • r r ■” j ~ ■ T'.-r' i-,c l' r ■ ■ TV'' ; f', • Lv q- ■nr -17- way as oxygen tmd that it also forms with coke and charcoal this same kind of surface compound in which the sulphur atom is in the position of the oxygen in the formula given. We could then say that sulphur comoines with a mass of carbon directly to form a solid complex, Cx^y, of variable composition, high in sulphur and low in carbon but in which the ratio of carbon to sulphur is not necessarily constant, and which is stable at ordinary temper- atures, As there was less of the oxygen present at the high tem- peratures we should exi)eot to find lov/er percentages of sulphur adsorbed at the higher temperatures, which has been amply verified in previous investigations. 17.H. Adolph^^ studying the surface compounds of sulphur and nitrogen comes to this same conclusion. He studied the interior and exterior of lumps of coal and coke and found a distinct excess of sulphur in the surfetse layer. -18- PART III PXPERB^IEITTAL A. The furnace emploiT-ed in tide investigi-tion was that used oy Dr. M.J. Bradley in this laboratory in his study of the decom- position products of coal carbonization^'^. It was made by taking a six foot length of four inch, Ho. 18 Byer’s pipe, thr^ing on flanges and thermocouple pockets and having these joints acetylene v/elded to insure having no leaks under high temperature conditions. The caps extend- one and one half inches into the furnace. The pipe was thinly coated on the outside with alundum cement, v/ound in five sections, each having 36i feet of Ho. 14 A chromel resis- tance wire, and again coated with cement. It was surrounded by a wooden box twenty inches square, and as long as the furnace, and containing pulverized asbestos and sil-o— cel insulation. Bach heating element when connected directly across the 110 volt line allowed a maximum current of 20 amperes to pass through, but this could be reduced to five amperes by means of an external slide wire resistance connected in series at the switchboard. 3y this means the heat of the furnace could be kept constant at any desir- ed temperature be.tween 250® and 900®0. The top end was fitted with a reservoir and feed pipes for CSg, superheated steam, etc., and also with a pressure guage and reduced pressure guage. At the bottom was a safety relief valve, or constant pressure valve v/hich could be adjusted to let the gases escape into the line leading to the wet-gas meter at any desired pressure. The temperature was measured by means of a thermo- couple made from six feet of Ho. 8 chromel and alumel wire. -19- The cold juotion was kept at zero ky means of a thermos bottle filled with ice water and the e.m.f. was read on a millivoltmeter which had been standardized at known temperatures. This gaYe readings accurate within four or five degrees. The interior of the furnace was also lined with alundum cement to prevent corro- sion by the sulphur compounds. 3. The CSg was piaced in a reservoir above the upper end of the furnace and by means of a regulating valve passed through a sight glass into the furnace. Eere also could be introduced gases, as hydrogen, and HgS from cylinders or generators, or steam from the high pressure line, through the gas fired super- heater tubeo Charcoal could also be heated to incandescence in this tube, forming water gas from the steam passed over it. In passing down through the furnace, the vapors came into contact v/ith the various carbon forms used. Two water cooled condensers collected any condensates in bottles, vliile the gases passed on through meters and were burned. At the completion of the runs the current was shut off from the switchboards, and the furnace allowed to cool down to about 150°C before opening. j • Gas samples v/ere taken in two liter aspirator bottles in which the v;ater had become saturated v;ith the gases in question. These were analyzed in the usual manner in a modified Orsat appa- ratus. The I/rehschmidt method of analyzing for sulphur content was found to be unsatisfactory in the work, owing to the small and variable amounts of gas coming through the furnace being in- sufficient to support a st ea4y flame under a trumpet tube. Eor mm - 20 - the H^S determinations a Tutweiler's burette with a standard iodine solution of Icc equal to one grain of sulphur per 100 cubic feet was found to be sufficiently accurate for the major- ity of determinations in which the percentage of ITgS was not too great. Two determinations w'ere made on each type of carbonace- ous substance taken from the furnace, one by shaving off the out- er one sixteenth inch of the coke or charcoal and the other from as near the center of the lump or stick as possible. These were pulverized in a porcelain mortar to 60 mesh and dried in an oven at 120°C for two hours, peroxide fusions were then made, and the sulphate precipitated from an acid solution by 10^ Bacig in the usual manner. This precipitate , after digesting on the steam bath for at least three hours, in no case presented difficulty in filtration with ordinary A.D.L. filter paper. The precipita- tes v/ere washed twice by decantation with v;ater, containing a little ECl to insure the removal of the last traces of iron and then transferred to the filter papers and washed with hot distil- led v/ater until tests with a silver nitrate solution showed all the chlorides to have been removed. The filter papers were dried in an oven and ignited carefully in porcelain crucibles and the BaS 04 calculated to percent of sulphur in the air dried sample. The best fusions were obtained with a charge of O.Sgrems of coke or charcoal, 0.75 grams of EGlOg, one scoopful of Ea202,(14 grams), and about 1.0 gram of sugar. P. To determine the area of the furnace in which the greatest reactions would take place, sample bundles of chercoal were placed in the furnace, one at the top, and one at the center, and the last near the lower end of the furnace, and passed through with the furnace at a temperature of £00°C. Analysis showed that the charcoal at the center of the furnace and the lower end ac- cumulated 0.60^ sulphur, ?/hile that at the upper end only It v»ras decided to place all succeeding charges as near the center as possiole. In order to determine the effects of the temperature of air drying and the physical form of the substance on the sulphur content of the impregnated carbon materials during this part of the sample preparation, a sample stick of charcoal was placed in the drying oven and heated for two hours at 120 ®C. An exterior and interior sample showed 9o04f. and 9ol6f^ sulphiir, respectively. Another stick of the seme run was first sampled, pulverized, and then placed in the oven end air dryed as before. This gave analy- ses of 6.92^ and &.6lfo for the exterior and interior samples re- spectively. It was accordingly decided to be necessary to first sample and pulverize the coke or charcoal before air drying, A third stick of charcoal, dried in this manner, was found to con- tain 10.725^ sulphur on the exterior and 7.25f^ on the interior. Fach sample was then returned to the oven and further air dried, with frequent stirring, for ten hours, after which they analyzed 6.34f and 4. 56^, respectively. Apparently some had merely been absorbed and was driven out by the continued heating. It was de- cided that the loss was not relatively large enough to warrant ^^ytng for such a long period of time and the two hour period was chosen for the standard for preparing the remaining samples. Analyses ?/ere also made for the various carbon substances used, and are shown in the following tables: c Substance S Exterior S Interior f Fe Metallurgical coke 1.08 0.97 1.47 Low Temperature coke 1.07 1.05 neglegible Petroleum coke 1.23 1.18 trace Wood charcoal 0.09 0.09 0 The metcllurgiGal and low temperature were hoth fair grades of coke, hard, and rather non-porous. The oil or petro- leum coke was obtained from the crude oil stills of the Standard Oil Company of Whiting , Indiana. It was of a very uniform com- position, very porous, and had 8 marked jet black iridescence. The charcoal was of a good grade of finely grained oak charcoal with a final carbonization temperature of about 550° to 600 °C. T?* • • In this first series of runs, about 750 cc of CSg per kilo- gram of crude carbon was vaporized and passed through the furnace at various temperatures for from 6 to 8 hours. Several referen- ces in the literature show that the coke and charcoal are being used commercially in the purification and removal of OSg from gas and it was to obtain more information about the action of CSg on crude carbon, that this part of the work ?^was undertaken. 46 W.E. Fulweiler makes the statement,'^ it seems to me that the man who is trying to make sulphur-free gas should study the organic sulphur compounds, which seem to vary in percentage _rom three to possibljr nine or ten. They are the compounds that are going to be difficult to remove by any method that we know at the present time, and if we are going to make a really sulphur- free gas they will have ^ be solved". After the normal gas purification it may still contain 8 to 43 grains of sulphur per I •i : I I,. '.'ii - ■rAvu -i ■. i ::■ ^.rr ^ \.c:j !■ , '.y-< V. C I. .. •.■.u : .( 'I’i ■■ • :-a:T •V • 'm' *>■ :■ '* ^ M , ,■ '.f c. c . ■; rj c.c O':*')- ' ■ V '}■ V ' I ■> '. ■'■fj j rcMiV . j j, i! I I n 1,5 ; S fr ' . -t r . , t':. ;.l. - r'“- - ;■ ZTTZ'CZ.'.. -23- leo cutic feet'^’^. J. Matwin^® descrilDes experiments in which one kilogram of wood charcoal lowered the sulphur content? of one cubic meter of gas from 100 to 29.9 grains per 100 cubic meters. The charcoal was regenerated by immersion in water for one hour and subsequent drying at 150°C. The removal effect of v/ater has been known for some time in the case of nitrogen and hydrogen sd- ■ sorption by charcoal'^^. H. l^anner found that one kilogram of charcoal purified E-G cubic meters of gas, containing 73.1 grains of sulphur, to 20 oO grains per 100 cubic feet, A recent British patent^^ covers the purification of gases of sulphur after the usual Tf^S removal by their passage over finely porous carbon or charcoal. The following tables show the amounts of sulphur found on the surface, also in the middle region of chunks of carbon substan- ces, after having been treated with the CSg &t the temperatures noted. Substance. Temp. ITo. ^Mineral S. f Final S.^ Increase in S. Fxter . Inter .Fxt.‘ Int . Fxterior Interior Charcoal 410 °C (1) 0.09 0.09 6.93 6.61 6.84 6.52 Charcoal 500°C fi) 0.09 0.09 11.07 9.29 10.96 9.20 Charcoal 500®C f2) *0.09 0.09 10.74 7.2E 10.65 7.16 Charcoal 695°C (1) 0.09 0.09 10. IE 10.52 10.06 9.43 Charcoal E9E°C (2) 0.09 0.09 9.82 9.45 9.73 9.36 Charcoal 700°C fl) 0.60 0.16 2.97 2.92 2.37 2.76 Metallurgical Coke 398®C fl) 1.08 0.97 1.56 1.55 0.48 0.58 Metallurgical Coke 39E°C (2) 1.08 0.97 1.30 1.01 0.22 0.04 low Temperature Coke 400°C il) 1.07 l.OE 1.16 0.89 0.09 - 0.16 Metallurgical Coke E00°c (1) 1.08 0.097 1.64 1.08 0.56 0.11 Metallurgical Coke 500 C fl) 1.43 1.28 1.68 1.48 0.25 0.20 Metallurgical Coke 600°C (1) 1.08 0.97 1.27 1.19 0.19 0.22 Metallurgical 1 -Hfl 0.97 1 .lA r.,nn n.i -24- substance Temp. Ho. f; Miners! S. Final B. ^ Increase in S. Fxter. Inter .Fxter. Inter. Fxter. Inter. Metallurgical Coke 700®C fl) l.OC 0.84 1.20 1.21 0.20 0.47 C TI ~ C6ke 70'0'^"TI1 1723 1718 ITU Z.Th 0 .TB 1740 ^ A second series of results for any given temperature are for an entirely new sample and not a duplicate analysis of the preced- ing sample. In most cases about 80^ of the CSg Vv^ss recovered in the conden- sate. The gases passing to the meter contained frDm40 to of CSg, 4.6 to 6.7f^ of CO 2 . 1»37 to 2.0^- unsaturated and 2.2 to 2.7f^ of saturated hydrocarbons, 4.7 to 11. 8^^ of Hg, 14.1 to 32.4^i of CO, and 1.5 to 4.55! of oxygen, with a very little methane, ethane, and benzene. In each case the furnace was swept out thoroughly with city gas befor making the runs but considerable oxj^gen, hydrogen, etc., must have been retained by the charcoal, and coke, to give such high percentages of oxygen and hydrogen, and their compounds, in the gas analyses. The most outstanding featiire of these results is the far greater percentage of sulphur found in the charcoal as compared to that in the coke. The former, being of an extremely porous nature, besides presenting an enorcious surface, with a correspond- ingly hi^h absorptive capacity, also offers the opportunity for capillary action. Lowry end Fulett have calculated the surface of charcoal to vary from 160 to 436 square meters per gram. With a material of this kind it is really meaningless to talk about the surface on which the adsorption can take piece. Langmuir^® states that charcoal probably consists of atoms combined together in branch ing chains of great complexity. Between the atoms of carbon there must be spaces of all possible sizes and shapes. There would be. -25- however, a fairly sharp limit to the number of molecules which could come into intimate contact with the carton atoms, the limit corresponding to the saturated state observable in adsorption even by porous bodies. It is seen that with both charcoal and coke, (except the oil coke) , a temperature of 500°C gives the highest sulphur con- tent, It is necessary to assume in all of our experiments that an equilibrium exists between the incandescent carbon and the dissoc- iated vapors employed. Thus ?/ith we will have the equations: CSg t heat ^ C 4* 2s 2S + C (coke or charcoal) — C^S^( surface com- ^ p ound ) IVe might assume that the atomic sulphur produced by the dissociation of CS„, in contact Vvith the incandescent carbon, forms the carbon- sulphur surface compound, 2Iow it has already been sta.ted that t he previous work on this theory indicates that the formation of the surface compounds is impaired at the higher tem- peratures, At the same time CSg is not known to dissociate at reasonably low temperatures. There must, hov:ever, be a certain temperature at which the two effects allow a maximum retention of sulphur, in this case 500^0* In general a distinct excess of sulphur is found in the sur- face samples, which is what we v/ould expect. In the case of the coke particularly, however, its hard, and non-porous nature must be considered as making an easy and thorough penetration of the CSg vapors to the center of the coke lumps a difficult and rather lengthy process. This probably accounts for the fact that the maximum percentage sulphur increase in the interior samples re- quires a higher temperature than that in the case of the maximum surface increase* -26- F. In the ordin&ry coking process there exists a considerable zone of temperature wherein the decomposition yieldsfixed gases QO practically free from sulphur . As has been previously stated, HgS is expelled during the coking process and must of necessity pass throughthe incandescent mass. What then becomes of it dur- ing the period of minimum sulphurgas production? hoes the H 2 S also form some organic sulphur compound with the carbon? It was with a view toward answering these questions that the reactions of KgS on the various forms of carbon were studied. Fussell^® studied these reactions quite extensively and found from his experiments with sugar carbon and EgS: (1) A determinati%^i7 Volume che'^nge of FgS could not be made applicable to this study. (2) A time-saturation study showed that only a very little additional sulphur is taken up after the first hour. (3) The activity of the carbon toward the H 2 S increases up to a temperature of about 770^0 and then after this there is a decrease in the amount of sulphur combined. Ee explained these results on the basis of the assumption that above 7C0°C the Eg formed by the dissociation of E^S has a greater tendency to re- move the sulphur than the carbon has to hold it. In the writer's work, HgS generated in a Kipp generator, and collected in large carboys over water, giving a constant de- livery to the furnace, was employed. At first it was mixed with the illuminating gas before entering the furnace, in order to in- sure a constant movement of the over the incandescent carbon. This was found to be impracticable hov/ever, owing to the difficult ■:m 6 f^ ur’ 9 fif\ , , v>X -. i'r-' ’> .' (.'i^<. 0 ‘ : .rJ ■ .V'uj;/ \ »' ■ ; : O’" f 9. . . ' »*- ^ j V ... ^ • .^ C 5 ; . uC V-.- -r;;.. .( .' , ;.-• (• ' ■ ■ ■ :' .. .V J- ,y^.; I'X / .! ' . y ^ ■■' ^ ■ 9 - ' *' .' ,^■•‘' " .* , »., 1*-^' ' * - ** . y • J i',.j „..’ V? .■'. t : ■.'' y’fS<: ■' ''■*-■■ ' *♦ s« - ._;C : ... .■ V ■■> - ' ., ' ■; ' *']rj.'‘..) ■ .vGr l*' .‘ . : Xo '■ ' , y \ ' ■f - i^T ^ jv:; *• 'I'f.’’!:' c .r; r • ‘ , J ’ '• • ■ ' ' ' \ . ■ ' , ...... . . .. . M. ■ >V’ ,l:‘ r^X'/.h !XJ • i' 5 ■ % X- ir.',. / v>. i! 0 ■;. :;.5. f‘--. . j j ; .) J vCj.' V •" f *»• ; ■ ■ .V >/.. »* (?. I » : VJC^: • <' rt . _ ■ K" f. 5^- ^ V •vcr'.* ^ •: TT- ;iij; ...c X'. , sjurt;'';- ' ,'t' f"*' ■ '! . " ),_i . C ^‘. ./‘J I A., - •; "_-r -»L, • \V, . M.., ; / *■ ' f r ' '2 ' ..AM - .. '■'■ 1 , ^ i' y. .- ■ I I '■.'.’ X .c <.. f.c j X ' T; ' ; - t • li 1,A ’ i - ■ y - * / . - .'i-' ...' ■: ■; X 4 ,r n,U' ■• yiy: ,' .* V' ,>'^j'r) ;r ■’' ■■■ .f.*X < X '];;j •'r., ^-.i Vf; .iTDOS t f>X :c :k ... c_ (Vvi,i;iiDX -•vT ■ ■ ■ ■^ - ....., •■>. i j j (• ■ ; ;. L, «- .t>;Av . l.}^ ; a rt ,'rc; ‘; ' 3 ^ •■• I i.:i :.i^i '■„' , ■•■ly. :•. ,' i: . ^ ' ‘ y . ' ■ . * i .V .V . . '.■J^;v '.r-'t . dvXT, r . ' 'Xr ' • • .. ■- gX •!)'): c j. •/ . ‘ J.. 4 ' - .i, X ^ ' d" 'i ■ VO , fj- ':c v'V . ''d'V6X«;r. : .L r ,: ■■ ' ■• •. , - ■ -C'-O ' f ' ' iV' - ,i I *,3 4 *“~^ 3 Waa .*#. i«#» ^ « ,*v— -'‘- • ■tl « ll ^ ... Jl -27- of regulating the pressure and of determining the amount of HgS being used. The collection of the H S over v/ater was also found unsatisfactory, hut much more succeseful than hy attaching the T'ipp generator direct to the furnace. The HgS was slowly passed through the furnace until gas analysis indicated that the carbon- aceous material was saturated. The results of these experiments follov/: Substence Temp • f. Initial S. ' ^ Final 3. Increase in S, Exter. Inter. Fxter. Inter. Fxter. Inter. Charcoal 580°C 1.23 1.18 1.27 0.60 0.04 -0.58 Charcoal 505°C 0.09 0.09 0.60 0.16 0.51 0.07 Charcoal 680°C 0.09 0.09 2.89 1.64 2.80 1.55 Met. Coke 380°C 1.08 0.97 1.10 0.76 0.02 -0.21 Oil Coke. 280°C 1.2S Xol6 1.53 1.57 0.30 0.39 Met. Coke 505°C 1.08 0.97 0.90 0.81 - -0.18 -0.16 Mete Coke 675°C 0.90 0.81 1.02 1.73 0.12 0.92 Met. Coke 680°C 1.08 0.97 1.22 1.27 0.14 0.30 Oil Coke 680°C 1.23 1.18 2.89 1.64 1.66 0.46 At lower temperatures the gas issuing from the furnace was so high in F2S ■ that the use of the Tutweiler burette was imp os sib On the run at 380^0 an Orsat analysis gave Kg S + OOg, 71. If; Og, unsaturated hydrocarbons. n • U . Hg, V.9 f; ana 00, 0.7f. At 6C5°C the results v/ere practically identical. At the start of the run at gases came through the furnace unchanged, but soon an analysis showed and C 02 , 11.9^; 0 £, 2.5<; Hg, B7.4f; and CO, 25 .8f . 1 On the run at 680 °C hardly a trace of KgS appeared in the outcoming gases and the orsat analysis showed FgS and COg , 0£, 3.2<; Fn, 77. and CO, 3 .7^. These results show, as did Russell’s that the greatest in- -28- oreese in percentege sulphur occurs st the higher temperatures. In general also, v/ith the exception of some of the results on the metallurgical coke, the exterior shows a higher percentage sul- phur than the interior samples. A peculiar result is to he • noted in the run at 380*^0. The interior of the charcoal and metallurgical coke apparently lost some of its sulphur with an increase in that in the oil coke, particularly in the interior. Ho plausible explanation suggests itself to the writer for this. That a true equilibrium must exist in this series of experiments is noticeably brought out in the run at 505°0. Both charcoal, with an extremely low percentage of sulphur, and metallurgical coke of medium content, were heated in the furnace together and exposed to the action of HgS . The charcoal increased in the percentage of sulphur but apparently at the expense of the sul- phur contained in the coke. Thus the carbon- sulphur combination of the coke must possess a vapor tension, or itself dissociate somewhat at this temperature, the resulting atomic sulphur act- ing on the carbon of the charcoal to reform the combination. For an explanation of the much higher temperature necessary to|pr educe s maximum increase in sulphur content we may turn to the literature on the studies of the dissociation of FoS. *52 Freuner*" gives the following data for the percentage dissocia- tion at various temperatures; 2,Zfj at 627°C, 16.4'^j at 947°0, 31.7^ at 1137'^C, and 76*lf^ at 1727®C. There would thus be little atomic sulphur available to combine with the car- Don, even at 680 Alscj as experiments already referred to, and the results of the next series of ours shows, hydrogen at this temperature causes a very great removal of the sulphur combin- -E9- ation, especially from charcoal. Thus we may account for the small increases in sulphur content, even in the charcoal, in the interaction with the H^S and carbon. Though the ^£3 evolved during the coking period is exceed- ingly smaller in amount than that employed in the above experi- ments, its reaction should be of the same general type as those just described. They have already been found of practical appli- cation to gas purification and may prove of greater value on fur- 53 ther study. T7.F. Lamoreaux and C.W. Eenv/ick give a process of removal of sulphur from furnace gases by passing through hot coke at a temperature maintained above 1000°C by passing an electric current through the coke. A. Engelhardt*"^ has patented a method to remove from gases by the use of activated charcoal. C-. Many references have previously been made to the high percentage of sulphur removed by hydrogen, particularly at tem- peratures above 500*^0. The hydrogen used in this series of runs was deliverrd directly into the furnace from cylinders. The results are given in the following table; Substance Temp. Mo. ^ Initial B. ^ Final S. Pecrea se in S Exter . Inter. Exter. Inter . Exter. Inter. Charcoal 530°C (1) 11.07 9.29 2.54 2 .36 76.1 74.6 Charcoal 530 °C (2) 10.74 7.25 2.51 2.24 76.6 69.1 Charcoal 600°C (1^ 10.95 8.27 1.66 1.9S 84.5 76.0 Charcoal 600°G (2) 8.71 7.90 2.83 3.29 56.0 41 . 6 Met. coke (1) 1 . 58 1 . 48 O' ."8 8 "0TM3~ Met. Cokef ret) 520 cJd) 1.10 1.05 0.76 0.70 30.9 33.3 Low. T emp .Coke 600 °C (1) 1.16 0.89 1.12 0.97 3.5 13.4 Lov/ . T emp . 0 okeSOC'C f2) 1.07 1.05 1.27 0.50 -0.20 52.4 The percentage decrease in sulphur is that percentage which the ^percentage of sulphur reduced is of the total percent- age originally in the sample before treatment. The first run was continued for ten hours to see if a -30- oomplete rffmovcl of tlie sulphur might be made. The gases leaving the furnace at the beginning of the run contained 1300 grains of sulphur per 100 cubic feet. At the end of 15 minutes it had de- creased to 1200, and ten minutes later to 1130. This rate of de- crees continued somewhat constantly until at the end of six hours it contained but 150 grains per 100 cubic feet, and an hour later this was 120 grains. Fowever, even at the end of 10 hours, the gas still gave a heavy precipitate v/ith CdOlp. This would seem to indicate that a complete elimination of sulphur could not be produced even after a long period of gaseous washing, making such a process commercially impracticable. The remainder of the gas in each case was practically pure hydrogen. The percentage decrease compares very favoraToly with the re- sults of other experimenters . The results with the lew temper- ature coke v/ould seem to indicate that the sulphur in it was pre- sent in it in a somewhat different state of combination than in the metallurgical coke, and charcoal. To explain the results on the basis of Langmuir’s theory it is necessary to assume some dis- sociation of the carbon- sulphur compounds|and removal as dis- placing the equilibrium of the carbon- sulphur combination towards its decomposition. TT X ' • The effect' of superheated steam for sulphur removal was next tried. The interaction of steam with the hot carbon within the furnace should produce hydrogen and CO and bring about a high sulphur removal. This was found to cause a rather excessive de- struction of the coke and charcoal, however, so additional runs were made in v/hicli charcoal was heated to incandescence in the gas Iv ■ • - • • -M-— . . •-.••v , ■■■;;'■ r •; ':.jc ' ' ■ ■' y ■■' w^' ■ V ‘J '' f";:'.' I’l: r*X. -■ , T r »' ■*^* I ' ' * ' ^ ■ j J f 4 f 'f' ■_ .t;/ ' ; I ■■ ■•' ) ''i;.4. ' '• ! *- • 0 i • -31- heated prelieater outside the furnace and the stec-in passed slowly over this giving the v;ater gos, as "before, "but not at the expense of the carhon substances of investigation. The results of these experiments are as follov/s: 5-ub stance . T emp . Ho. fa Initial S. f. Final S. i)ecre ase in ( ste Hxter . Inter. Hxter . Inter. Ex;ter. Inter Charcoal 425°C (1^ 10.96 8.27 2.76 2.70 74.6 67.3 Charcoal 425^0 (2) 8.71 7.90 3.47 4.18 60.0 47.3 Charcoal 425°C (3) 2.53 2.30 1.40 1.70 44.2 26.2 Tilet. Coke 510°C fl] 1.43 1.28 1.12 0.93 21.7 27.3 (water , psl~ Charcoal 680°C (1) 2.97 2.92 0.57 0.43 80.7 85.2 I'et. Coke 680°C (1) 1.20 1.21 0.80 0.85 33.3 29.9 Oil Coke 680°C fl^ 1.41 2.58 1.40 1.21 0.7 53.0 Considerable V v/as produced. particularly in the runs 0 using water gas. In the one at 680 C the gas showed 60 grains of suphur per 100 cubic feet at the end of the second hour, and 260 grains at the end of the fourth. A gas analysis taken be- tv/een these tv/o times gave HgS t 002,6.7^;0£, 0.8f; Ho, 68.3'^; and GO, 23. The use of the water gas gave in general even better reducf- tion than did hydrogen, and has tie added advantage of low cost and ready preparation. The higher temperatures produced the maximum sulphur removal and the samples containing the highest original percentage of sulphur showed the highest reduction. It is also to be noticed ths.t in a majority of the determinations the exterior samples of the treated carbon substances shewed a lower percentage of sulphur than the interior samples of the same. To account for the large percentage reduction in the interior of tl.e oil coke both in these runs and those employing hydrogen, v;hile the exterior remained practically unchanged, or as in the ease of hydrogen actually added 0.2f sulphur, it ; .. ) v/ould appear that the outside of the coke differs from the inter- ior. It may he that the latter still retains some of the crude oil hydrocarbons from the distillation which aid the sulphur re- moval from the interior. Iwosdz^^ studied the reactions in water £;ps formation and states that the primary reaction is expressed by the equation, C f HgO CO Eg The CO further reacts with the excess stesm, tending to form CO 2 and more hydrogen, thus; CO -h ► COg + Eg The result is the establishment of a "v/ater gas equilibrium” for each temperature employed. All three products of thi£^^®composi- tion have marked reducing effects on the carbon- sulphur compounds. 29 Chiles wishes to assume that there is a formation of a carbon- hydrogen surface compound v/hich CO might displace giving nascent hydrogen, which in turn could decompose the corresponding amount of the carbon- sulphur combination. I . To further study the remove! of these carbon- sulphur com- pounds of coke and charcoal, experiments v;ere made with x^’-lene and ordinary city gas. The results of these runs are given in the following table: Substance. Vapor. Temp. < Initial S. ^ Final s. 5 Pecrease in 8 . Exter . Inter • Bxter. Inter. Fxter . Inter. Charcoal Xylene 460°C 9.89 9.89 8.71 7.90 13.6 21.0 Charcoal City Cas450°C S.89 1.64 0.96 1.02 6608 37.8 ITet . Coke City Gas4509c 1.22 1.27 0.90 0.84 26.4 33.8 Oil Coke City (xas450°C 2.89 1.64 1,68 1,69 41.7 -0.05 These data show that xylene is much less effective thr-n city gas, and that the latter prodiices a relatively high reduction X ( u t even at as low a temperature as 4£0°C. The removal in the case of the xylene was probably due to the hydrogen produced by its decom- position, a gas analysis showing 7.5^? to be present at the temper- ature employed. It is also probable that this is the constituent which was most active in producing the effectiveness of the ordin- ary city gas. ' 1' * .. V if '"' fH :'ifc% 2 tio VU L'-'v6,r.0'i .j'V'' ' .''^■ti!^ P4' nofys '*[^' ■ " ^ ■' \ ■ ’Vi '''' ' '■ '^ ^ ' .. !l*<' , \ •■>*!L^sr. • ■ ^ \ — • ti f #Bf' '■'. .'..v .' 'ifc’xy'i'*- ’. •■ ■' ' ■ ‘ ■ -Sit,*''' ■' K- > ;■ • Mui ' nu 'J-i-a .* '-‘irr ff ■%, ■, ‘V ' e li 1.^ -f *■ ^ ^ 1 ' ' ' ' • ' • 'iW™ >> ■■ W • .A.’vyTI t'.f I. . " i> ' - (V'l *■ ■? iv ' ' ■‘ j. f»2!*|.:fe-.' ^S'i .•-■ ■■;ifcM' -"B % •' W' > . ' ' T- ' > •*: " ', '"A* ■' , '■.'Wi 1 KJ t - ■ liw '"1 f- - ■mA'^ .. ■ ■ *■ • •■ *,' f I . iA. ' 't ' >, ' ' w 'IV* '■^>T \ f-' *i-. •• ■ - f T f *-'■". lr»v)i • ' ■' ;k. »- ' hfy - ■ '#‘v . , , ,1, ,y ,;■?•*.• ., .1v \ ■» ■''j ». ■*„•«- V; „',' :7^J >dKjB^H|U|KKffi ^ .-' 'WHUW /; •, ‘ ■ ,' '•! , '. : ', \ , , ■ '^v ■ ' r '®^JNS .hi.. ■ >■ '.it J: ,. , .: V. '^3 , m«.i ■’> ' ''^' ■ ;"'■■••- . ./ ^3! .. "'; r. H,,.. '. :-.rs g ^ ■• IttV' , ' . V •.;’n^ I Wi ■ II 4 I". . fl -54- P4BT 17 sm:i^AEY 1. Wood charcoal is much more active than metallurgical, low temperature, or petroleum coke in its adsorption of sulphur from CSg and H2S, a.lso in the subsequent removal of sulphur by gases. 2. The most effective temperature for the combins.tion of sulphur from OS2 is 500^0. A sulphur content of 0,09fj in char- coal was increased to 11.07 and 9.29f, respectively, in exterior and interior samples in a determination of this temperature. Metal- lurgical coke increased from 1.08 and 0.97fj to 1.64 and 1.08^. 5. The sulphur from H23 is best taken up at 680°C, the per- centage sulphur in charcoal increasing from 0.09^^ to 2.89^ and 1.64^, and in metallurgical coke from 1.08 and C.9'7fj to 1.22^3 and 1.27f^. 4o In general the exterior samples from these experiments show a higher sulphur percentage than the interior ones. It is quite probable that if the reaction be continued long enough the two will become equal. 5. Hydrogen is a very effective agent for desulphurization, reducing the sulphur content of charcoal from 11.07 and 9.29f^ to 2^54 and 2. 36f^, respectively in the exterior and interior samples. That of coke is reduced from 1.68 and 1.48 to 0.88 and 0.83^. 6. Steam causes excessive oxidation of carbonaceous mater- ial. 7. Water gas is the most effective ageit of all, reducing the sulphur content of charcoal from 2.97 and 2.92f! to 0.£7 and 0.43^ and that of metallurgical coke from 1.20 and 1.21^to 0.81 and 0.8£«^. 6. Xylene is not very satisfactory for desulphurization. 3. Ordinary city gas is very effective, reducing the sul- phur content of charcoal from 2.89 and l,64fj to 0.97 and 1.02f^, and that of metallurgical coke from 1.2? and 1.27^ to 0.90 and 0.84f^ 10. After treatment by gases the exterior samples of the coke and charcoal generelljr contain less sulphur than the interior samples. They would probably become equal, hov;ever, if the treat- ment were continued for a long enough period of time. 11» It is probably impossible to entirely eliminate the sul- phur from hot coke by means of gaseous washing, and even if it v/ere the length of time required would make the process commercial- ly Impracticable, in all probability. 12. The use of hot carbon to remove the organic sulphur com- pounds from gases may prove of commercial importance, but is pro- bably not praotioal for the removal of K„S. 2 ^ . 13. The decided action of water gas, h^^drogen, and illuminat- ing gas in lowering the sulphur content of coke and charcoal in- dicates that desulphurization by passage of such gases through the coking mass may prove of commercial value. 14* In general the distribution of the sulphur on the in- terior of the carbonaceous material on treatment with OSg and EgS is as follows: Below 400°C the sulipiiiir shiifts from the interior to the exterior; tbove this temperature up to 675*^0 in the cf^se of the metallurgical coke, and 680°C v;ith the charcoal, the sulphur in- creases in both the interior and the exterior but a greater percent- age in the latter. Above these temperatures the sulphur continues to increase, but is greater in the interior samples. -26- PAI^T V BI3LI0GRAPFTY 1. Ohemo Trade J. 52,211 2. 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Zeit. fur Anal. Chem. (1868), 445 27. Pull. iju. I.M. M.E. (1919), sept . Supl., 2436 28. Am. Chem J. 4, 8-16 28a 0 Chem. Eng. (1910) , ]^, 27 29. Bull. A.I.H. A M.E. (1919), 1807-9 30. Lewes, "The Carhonization of Coal" (1912), 274 31. Chem. Hews (1876), 147 32. Fuel (1878), 344 33. Am. J. Science(*)( 1386) , 251; Compt. Ptend. 74, 180^ 51.32 34. J, Of the Chem. Soc. (1865), 3^, 285; and(1868), 21, 186 35. Am. J, Science (3rd Series) (1893), 373 36o Pec. Trav. Chim. (1919), 159-62 37. Thesis, U. of I. (1919) 38. Thesis, T7. Of I. (1920) 39. Thesis, U. of I. (1920) 40. Physics Peview (1915) 6, 79-80; (1916), £, 149-76, - J.A.C.S. (1916), 2221-95; (1917), 39, 1848-1906, 2849; (1918), 40, 1361-1403. 41. J.Soc. Chem. I. (1905), 473 42. J.C.S. (1912), 2^, 831 43. J.A.C.S. (1920), 1393 44. Peport on "The petention of S and IT in Coke in the form of Surface Compounds", U. of I. (1921) 45. Thesis, U. of I. (1921) 46. Fin. c’. Met . (1920), #157, Sect. 12, 65 47. Cas Trorld (1919) , 70, 39 X f t -58- 48. J. Gas bel. (1909), 52, 602-4 49. GillDerts Annal. der Physiks (18 4), 122 50. J. Gasbel, ( 58] , 456-7 51. British patent ,149,911, July 28, 1920, and 165,761, Aug. 31, 1920 52. Zeit. Anorg. Ohein. (1907), 279-88 53. British Patent 2834, Peh 22, 1915 54. Zeit. fur Angew. Chem. (1921), 3_4, 314-20 55. Zeit. fur Angew. Cheiii. (1918), 31, I, 137-40