900:
118:
poisoning of the catalyst. Conversely, if the reaction rate is fast compared to the rate of diffusion, a poisoned shell will form on the exterior layers of the catalyst, a situation known as "pore-mouth" poisoning, and the rate of catalytic reaction may become limited by the rate of diffusion through
927:
S and hydrocarbons of varying chain length. Common catalysts used are tungsten and molybdenum sulfide. Adding cobalt and nickel to either edges or partially incorporating them into the crystal lattice structure can improve the catalyst's efficiency. The synthesis of the catalyst creates a supported
910:
Usually, catalyst poisoning is undesirable as it leads to the wasting of expensive metals or their complexes. However, poisoning of catalysts can be used to improve selectivity of reactions. Poisoning can allow for selective intermediates to be isolated and desirable final products to be produced.
104:
to a catalyst's active sites. Poisoning decreases the number of active sites, and the average distance that a reactant molecule must diffuse through the pore structure before undergoing reaction increases as a result. As a result, poisoned sites can no longer accelerate the reaction with which the
47:
Organic functional groups and inorganic anions often have the ability to strongly adsorb to metal surfaces. Common catalyst poisons include carbon monoxide, halides, cyanides, sulfides, sulfites, phosphates, phosphites and organic molecules such as nitriles, nitro compounds, oximes, and
312:
648:
659:
555:
131:
If the catalyst and reaction conditions are indicative of low effectiveness, selective poisoning may be observed, where poisoning of only a small fraction of the catalyst's surface gives a disproportionately large drop in activity.
113:
include steps to remove potential poisons from the product stream. When the poisoning reaction rate is slow relative to the rate of diffusion, the poison will be evenly distributed throughout the catalyst and will result in
210:
439:
In this case, the catalyst effectiveness factors are considerably less than unity, and the effects of the portion of the poison adsorbed near the closed end of the pore are not as apparent as when
664:
434:
221:
957:. Lead alloys with the metals present in the catalyst, while lead oxides and halides coat the catalyst's surfaces, reducing the converter's ability to reduce NOx emissions.
48:
nitrogen-containing heterocycles. Agents vary their catalytic properties because of the nature of the transition metal. Lindlar catalysts are prepared by the reduction of
895:{\displaystyle {\begin{aligned}F&={\frac {v_{\rm {poisoned}}}{v_{\rm {unpoisoned}}}}\\&={\frac {\tanh\coth h_{\rm {T}}}{1+\alpha h_{\rm {T}}\tanh}}\end{aligned}}}
387:
This represents the "classical case" of nonselective poisoning where the fraction of the activity remaining is equal to the fraction of the unpoisoned surface remaining.
382:
566:
455:
653:
The fraction of the catalyst surface available for reaction can be obtained from the ratio of the poisoned reaction rate to the unpoisoned reaction rate:
1242:
Kishan, G; Coulier, L; Van Veen, J.A.R; Niemantsverdriet, J.W (2001). "Promoting
Synergy in CoW Sulfide Hydrotreating Catalysts by Chelating Agents".
1207:
Cheng, F. Y; Chen, J; Gou, X. L (2006). "MoS2–Ni
Nanocomposites as Catalysts for Hydrodesulfurization of Thiophene and Thiophene Derivatives".
23:
by a chemical compound. Poisoning refers specifically to chemical deactivation, rather than other mechanisms of catalyst degradation such as
919:
In the purification of petroleum products, the process of hydrodesulfurization is utilized. Thiols, such as thiophene, are reduced using H
156:
27:
or physical damage. Although usually undesirable, poisoning may be helpful when it results in improved catalyst selectivity (e.g.
92:
in order to lower the catalyst activity and thereby prevent over-reduction of the aldehyde product to the primary alcohol.
964:
using platinum catalysts, the fuels must be free of sulfur and carbon monoxide, unless a desulfurization system is used.
1171:
1150:
449:
The rate of diffusion of the reactant through the poisoned region is equal to the rate of reaction and is given by:
119:
the inactive shell. Homogenous and "pore-mouth" poisoning occurrences are most frequently observed when using a
403:
307:{\displaystyle F={\sqrt {1-\alpha }}\,\tanh \left(h_{\rm {T}}{\sqrt {1-\alpha }}\right)\coth h_{\rm {T}}}
355:
110:
215:
When the ratio of the reaction rates of the poisoned pore to the unpoisoned pore is considered:
32:
987:
967:
28:
24:
983:
1106:
Lindlar, H.; Dubuis, R. (1966). "Palladium
Catalyst for Partial Reduction of Acetylenes".
643:{\displaystyle v=\eta \pi \langle r\rangle (1-\alpha )\langle L\rangle k_{1}''c_{\rm {c}}}
8:
1280:
938:
550:{\displaystyle {\vec {v}}_{\rm {diffusion}}=-\pi \langle r^{2}\rangle D{\vec {\nabla }}c}
61:
1275:
1224:
1055:
1013:
49:
1091:
1074:
1051:
1189:
1167:
1146:
1108:
950:
81:
1228:
1059:
1251:
1216:
1117:
1086:
1047:
1018:
954:
1008:
105:
catalyst was supposed to catalyze. Large scale production of substances such as
946:
942:
147:
77:
1184:
Satterfield, Charles N.; Sherwood, Thomas K. (1963). Hoelscher, Harold (ed.).
1269:
1121:
979:
120:
101:
1255:
1220:
975:
57:
982:, etc.) are poisoned by water and oxygen. This poisoning applies to both
115:
65:
36:
971:
1241:
1188:. Massachusetts Institute of Technology: Addison-Wesley. p. 94.
995:
961:
89:
73:
991:
69:
20:
106:
1193:
85:
205:{\displaystyle \eta ={\frac {\tanh h_{\rm {p}}}{h_{\rm {p}}}}}
1038:
335:
The above equation simplifies depending on the value of
139:
is the effectiveness factor of the poisoned surface and
990:
for olefin polymerization. This requires the monomers (
1037:
31:). An important historic example was the poisoning of
928:
hybrid that prevents poisoning of the cobalt nuclei.
662:
569:
458:
406:
358:
224:
159:
560:
And the rate of reaction within a pore is given by:
1183:
328:is the Thiele modulus for the unpoisoned case, and
905:
894:
642:
549:
428:
376:
306:
204:
914:
332:is the fraction of the surface that is poisoned.
1267:
84:) is intentionally poisoned by the addition of
321:is the ratio of poisoned to unpoisoned pores,
1105:
1206:
612:
606:
588:
582:
526:
513:
42:
1164:Industrial catalysis: a practical approach
1072:
1137:
1135:
1133:
1131:
19:is the partial or total deactivation of a
1143:An Introduction To Chemical Engine Design
1090:
244:
100:Poisoning often involves compounds that
1128:
941:used on automobiles, the combustion of
1268:
1156:
1099:
126:
52:in a slurry of calcium carbonate (CaCO
1075:"Mechanisms of Catalyst Deactivation"
429:{\displaystyle F={\sqrt {1-\alpha }}}
95:
1145:, John Wiley & Sons Inc., 1977
13:
1186:The Role of Diffusion in Catalysis
876:
840:
817:
796:
745:
742:
739:
736:
733:
730:
727:
724:
721:
718:
706:
703:
700:
697:
694:
691:
688:
685:
634:
535:
498:
495:
492:
489:
486:
483:
480:
477:
474:
298:
262:
194:
181:
14:
1292:
931:
342:. When the surface is available,
906:Benefits of selective poisoning
1235:
1200:
1177:
1073:Bartholomew, Calvin H (2001).
1066:
1031:
915:Hydrodesulfurization catalysts
882:
867:
855:
852:
802:
787:
775:
772:
603:
591:
538:
466:
1:
1092:10.1016/S0926-860X(00)00843-7
1052:10.1016/S0920-5861(99)00074-7
1024:
56:) followed by poisoning with
1079:Applied Catalysis A: General
7:
1002:
397:is very large, it becomes:
377:{\displaystyle F=1-\alpha }
10:
1297:
945:produces elemental lead,
60:. In a related case, the
43:Poisoning of Pd catalysts
1122:10.15227/orgsyn.046.0089
998:, etc.) to be purified.
988:heterogeneous catalysts
968:Ziegler-Natta catalysts
150:for the poisoned case:
1256:10.1006/jcat.2001.3203
1221:10.1002/adma.200600912
970:for the production of
896:
644:
551:
430:
378:
308:
206:
984:homogeneous catalysts
897:
645:
552:
431:
379:
309:
207:
25:thermal decomposition
1244:Journal of Catalysis
939:catalytic converters
660:
567:
456:
404:
356:
222:
157:
33:catalytic converters
627:
127:Selective poisoning
111:Haber–Bosch process
62:Rosenmund reduction
1209:Advanced Materials
1166:, Wiley-VCH, 2006
1014:Reaction inhibitor
892:
890:
640:
615:
547:
426:
374:
304:
202:
50:palladium chloride
29:Lindlar's catalyst
17:Catalyst poisoning
1141:Charles G. Hill,
1109:Organic Syntheses
951:lead(II) chloride
886:
751:
541:
469:
424:
279:
242:
200:
96:Poisoning process
82:calcium carbonate
1288:
1260:
1259:
1239:
1233:
1232:
1204:
1198:
1197:
1181:
1175:
1160:
1154:
1139:
1126:
1124:
1103:
1097:
1096:
1094:
1070:
1064:
1063:
1046:(2–3): 165–181.
1035:
1019:Enzyme inhibitor
955:lead(II) bromide
901:
899:
898:
893:
891:
887:
885:
881:
880:
879:
845:
844:
843:
823:
822:
821:
820:
801:
800:
799:
764:
756:
752:
750:
749:
748:
711:
710:
709:
678:
649:
647:
646:
641:
639:
638:
637:
623:
556:
554:
553:
548:
543:
542:
534:
525:
524:
503:
502:
501:
471:
470:
462:
435:
433:
432:
427:
425:
414:
383:
381:
380:
375:
313:
311:
310:
305:
303:
302:
301:
285:
281:
280:
269:
267:
266:
265:
243:
232:
211:
209:
208:
203:
201:
199:
198:
197:
187:
186:
185:
184:
167:
1296:
1295:
1291:
1290:
1289:
1287:
1286:
1285:
1266:
1265:
1264:
1263:
1240:
1236:
1205:
1201:
1182:
1178:
1161:
1157:
1140:
1129:
1104:
1100:
1071:
1067:
1040:Catalysis Today
1036:
1032:
1027:
1009:Hydrogen purity
1005:
943:leaded gasoline
934:
926:
922:
917:
908:
889:
888:
875:
874:
870:
839:
838:
834:
824:
816:
815:
811:
795:
794:
790:
765:
763:
754:
753:
717:
716:
712:
684:
683:
679:
677:
670:
663:
661:
658:
657:
633:
632:
628:
619:
568:
565:
564:
533:
532:
520:
516:
473:
472:
461:
460:
459:
457:
454:
453:
445:
413:
405:
402:
401:
396:
357:
354:
353:
349:is negligible:
348:
341:
327:
297:
296:
292:
268:
261:
260:
256:
255:
251:
231:
223:
220:
219:
193:
192:
188:
180:
179:
175:
168:
166:
158:
155:
154:
144:
129:
102:chemically bond
98:
76:catalyst (over
55:
45:
12:
11:
5:
1294:
1284:
1283:
1278:
1262:
1261:
1234:
1199:
1176:
1155:
1127:
1098:
1085:(1–2): 17–60.
1065:
1029:
1028:
1026:
1023:
1022:
1021:
1016:
1011:
1004:
1001:
1000:
999:
965:
958:
947:lead(II) oxide
933:
932:Other examples
930:
924:
920:
916:
913:
907:
904:
903:
902:
884:
878:
873:
869:
866:
863:
860:
857:
854:
851:
848:
842:
837:
833:
830:
827:
819:
814:
810:
807:
804:
798:
793:
789:
786:
783:
780:
777:
774:
771:
768:
762:
759:
757:
755:
747:
744:
741:
738:
735:
732:
729:
726:
723:
720:
715:
708:
705:
702:
699:
696:
693:
690:
687:
682:
676:
673:
671:
669:
666:
665:
651:
650:
636:
631:
626:
622:
618:
614:
611:
608:
605:
602:
599:
596:
593:
590:
587:
584:
581:
578:
575:
572:
558:
557:
546:
540:
537:
531:
528:
523:
519:
515:
512:
509:
506:
500:
497:
494:
491:
488:
485:
482:
479:
476:
468:
465:
443:
437:
436:
423:
420:
417:
412:
409:
394:
385:
384:
373:
370:
367:
364:
361:
346:
339:
325:
315:
314:
300:
295:
291:
288:
284:
278:
275:
272:
264:
259:
254:
250:
247:
241:
238:
235:
230:
227:
213:
212:
196:
191:
183:
178:
174:
171:
165:
162:
148:Thiele modulus
142:
128:
125:
97:
94:
78:barium sulfate
53:
44:
41:
9:
6:
4:
3:
2:
1293:
1282:
1279:
1277:
1274:
1273:
1271:
1257:
1253:
1249:
1245:
1238:
1230:
1226:
1222:
1218:
1214:
1210:
1203:
1195:
1191:
1187:
1180:
1173:
1172:3-527-31144-0
1169:
1165:
1159:
1152:
1151:0-471-39609-5
1148:
1144:
1138:
1136:
1134:
1132:
1123:
1119:
1115:
1111:
1110:
1102:
1093:
1088:
1084:
1080:
1076:
1069:
1061:
1057:
1053:
1049:
1045:
1041:
1034:
1030:
1020:
1017:
1015:
1012:
1010:
1007:
1006:
997:
993:
989:
985:
981:
980:polypropylene
977:
973:
969:
966:
963:
959:
956:
952:
948:
944:
940:
936:
935:
929:
912:
871:
864:
861:
858:
849:
846:
835:
831:
828:
825:
812:
808:
805:
791:
784:
781:
778:
769:
766:
760:
758:
713:
680:
674:
672:
667:
656:
655:
654:
629:
624:
620:
616:
609:
600:
597:
594:
585:
579:
576:
573:
570:
563:
562:
561:
544:
529:
521:
517:
510:
507:
504:
463:
452:
451:
450:
447:
442:
421:
418:
415:
410:
407:
400:
399:
398:
393:
388:
371:
368:
365:
362:
359:
352:
351:
350:
345:
338:
333:
331:
324:
320:
293:
289:
286:
282:
276:
273:
270:
257:
252:
248:
245:
239:
236:
233:
228:
225:
218:
217:
216:
189:
176:
172:
169:
163:
160:
153:
152:
151:
149:
145:
138:
133:
124:
122:
121:porous medium
117:
112:
108:
103:
93:
91:
87:
83:
79:
75:
71:
67:
63:
59:
51:
40:
38:
34:
30:
26:
22:
18:
1247:
1243:
1237:
1215:(19): 2561.
1212:
1208:
1202:
1185:
1179:
1163:
1162:Jens Hagen,
1158:
1142:
1113:
1107:
1101:
1082:
1078:
1068:
1043:
1039:
1033:
976:polyethylene
923:to produce H
918:
909:
652:
559:
448:
440:
438:
391:
389:
386:
343:
336:
334:
329:
322:
318:
316:
214:
140:
136:
134:
130:
99:
66:acyl halides
58:lead acetate
46:
16:
15:
1250:: 194–196.
972:polyolefins
116:homogeneous
37:leaded fuel
1281:Fuel cells
1270:Categories
1174:, page 197
1153:, page 464
1025:References
962:fuel cells
446:is small.
123:catalyst.
1276:Catalysis
996:propylene
865:α
862:−
850:
832:α
809:
785:α
782:−
770:
613:⟩
607:⟨
601:α
598:−
589:⟩
583:⟨
580:π
577:η
539:→
536:∇
527:⟩
514:⟨
511:π
508:−
467:→
422:α
419:−
372:α
369:−
290:
277:α
274:−
249:
240:α
237:−
173:
161:η
90:quinoline
74:palladium
70:aldehydes
1229:98052306
1194:63-16570
1060:19737702
1003:See also
992:ethylene
625:″
21:catalyst
146:is the
109:in the
107:ammonia
1227:
1192:
1170:
1149:
1116:: 89.
1058:
974:(e.g.
953:, and
317:where
86:sulfur
72:, the
1225:S2CID
1056:S2CID
390:When
1190:LCCN
1168:ISBN
1147:ISBN
986:and
847:tanh
806:coth
767:tanh
287:coth
246:tanh
170:tanh
1252:doi
1248:200
1217:doi
1118:doi
1087:doi
1083:212
1048:doi
960:In
937:In
135:If
88:or
80:or
68:to
64:of
35:by
1272::
1246:.
1223:.
1213:18
1211:.
1130:^
1114:46
1112:.
1081:.
1077:.
1054:.
1044:52
1042:.
994:,
978:,
949:,
39:.
1258:.
1254::
1231:.
1219::
1196:.
1125:.
1120::
1095:.
1089::
1062:.
1050::
925:2
921:2
883:]
877:T
872:h
868:)
859:1
856:(
853:[
841:T
836:h
829:+
826:1
818:T
813:h
803:]
797:T
792:h
788:)
779:1
776:(
773:[
761:=
746:d
743:e
740:n
737:o
734:s
731:i
728:o
725:p
722:n
719:u
714:v
707:d
704:e
701:n
698:o
695:s
692:i
689:o
686:p
681:v
675:=
668:F
635:c
630:c
621:1
617:k
610:L
604:)
595:1
592:(
586:r
574:=
571:v
545:c
530:D
522:2
518:r
505:=
499:n
496:o
493:i
490:s
487:u
484:f
481:f
478:i
475:d
464:v
444:T
441:h
416:1
411:=
408:F
395:T
392:h
366:1
363:=
360:F
347:T
344:h
340:T
337:h
330:α
326:T
323:h
319:F
299:T
294:h
283:)
271:1
263:T
258:h
253:(
234:1
229:=
226:F
195:p
190:h
182:p
177:h
164:=
143:p
141:h
137:η
54:3
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