Heat Stability of Molybdena-Alumina Dehydrocyclization Catalysts

Abstract

The heat stability in dry air of molybdena-alumina catalysts has been measured as a function of alumina type, alumina area, and molybdena concentration.

The Dehydrocyclization Reaction.

“…Ethylbenzene, toluene, 0-, m-, and p-xylenes (66) 3,3-Dimethylhexane........ Pt-carbon 1,1-Dimethylcyclohexane, toluene, m-xylene (79,80) 2,5-Dimethylhexane........ Active carbon, Fe-carbon p-Xylene Ce02-Al203; V203-A1203; Th02-Al203 Pd-Cr203; Ni-Cr203; Cu-Cr2ü3; Zn0-Cr203; Mo02-Cr203; Mn0-Cr203; Si02-Cr203; Aromatics (113,114) Aromatics (40,154) m-Xylene ( 91) Benzene (92) Toluene (40,54,65,69,105,111,113,114,132,145,154,159,160) Toluene (20,66,100,111,147,153,160) Toluene (20,153) Toluene (37,153) Toluene (54) Toluene (51,65,143,144,160) Toluene ( 75)…”

Preparation and Properties of Catalysts

“…The dehydrocyclization activity of molybdenaalumina and chromiaalumina catalysts has been the subject of much research. Webb, Smith, and Ehrhardt (47) and Claussen and Wellmen (12) claim superiority of coprecipitated molybdena-alumina over the impregnated variety, although Russell and Stokes (34) indicated that, if not handled properly in process operation, its stability may be no greater. The dehydrocyclization activity of chromiaalumina catalysts has long been recognized as greater than that of molybdena-alumina at atmospheric pressure.…”

Pyrolytic and Catalytic Decomposition of Hydrocarbons

“…Russell and Stokes (91) investigated the heat stability of molybdena-alumina dehydrocyclization catalysts. The dehydrocyclization of n-heptane to toluene is increased as the catalysts are calcined at temperatures from 600°to 700°C ., while at higher calcination temperatures the activity is lowered.…”