PROCESS FOR THE PREPARATION OF REGENERABLE NOBLE METAL CATALYSTS AND USE OF CATALYSTS THUS PREPARED IN THE CONVERSION OF HYDRO CARBONS

摘要

1356383 Hydrocarbon conversion SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ NV 3 May 1971 [4 May 1970] 21261/70 Heading C5E [Also in Division B1] Hydrocarbon conversion reactions, for example cracking, hydrocracking, hydrogenation, dehydrogenation, isomerization, hydroisomerization, alkylation, dealkylation, cyclization, dehydrocyclization and reforming, are effected by contacting hydrocarbon feed with catalyst which comprises carrier material, at least one Group VIII noble metal and at least one "additional" metal (defined as a metal having a Pauling type electronegativity value, as given in the table on page 78 of "Inorganic Chemistry" (1967) by R. T. Sanderson, which is greater than 1À6 but less-than 2À0) and which has been prepared by a process wherein at least one decomposable compound of at least one Group VIII noble metal and at least one decomposable compound of at least one "additional" metal are applied to a carrier which has been prepared by calcining at a temperature above 300‹ C., preferably between 400 and 550‹ C., a composite of porous carrier material (or precursor thereof) and at least one decomposable compound of at least one "additional metal", at least one "additional" metal being common to the compound(s) composited with the carrier material and to the compound(s) applied to the carrier unless a compound of tin is the compound (or one of the compounds) composited with the carrier material. The carrier may be prepared by a technique involving either impregnation or coprecipitation, followed by calcining which preferably is effected in a gas comprising oxygen, for example air. The Group VIII noble metal compound(s), which must be applied to the carrier either prior to or at the same time as application of the "additional" metal compound(s) to the carrier, and the "additional" metal compound(s) may be applied to the carrier by techniques involving one or more of impregnation, ion-exchange and precipitation, for example by impregnation either in a single step or in two steps with intermediate calcining, followed by calcining and heating in a gas comprising hydrogen; the or each calcining, which preferably is effected in a gas comprising oxygen, for example air, and the heating in a gas comprising hydrogen, which gas may be hydrogen per se, are effected at a temperature preferably above 300‹ C. but not exceeding 550‹ C. The porous carrier material, which may be amorphous or crystalline, preferably has a surface area greater than 50 m.SP2/SP/g. and an average pore diameter of at least 70 Šngstr÷ms; specified carrier materials are silica, alumina, zirconia, thoria, magnesia, boria, silica-alumina, silica-zirconia, mordenite, faujasite, zeolite omega and mixtures of alumina and mordenite. Specified Group VIII noble metals are ruthenium, rhodium, palladium, osmium, iridium and platinum; specified "additional" metals are copper, silver, cadmium, mercury, indium, thellium, germanium, tin, lead, bismuth, molybdenum, tungsten, technetium, rhenium, iron, cobalt and nickel. The catalyst, which may be acidic or non-acidic, may contain from 0À2 to 10 weight per cent of "additional" metal derived from the compound(s) composited with the carrier material, from 0À01 to 5 weight per cent of "additional" metal derived from the compound(s) applied to the carrier and from 0À01 to 3 weight per cent of Group VIII noble metal, the atomic ratio of "additional" metal derived from the compound(s) applied to the carrier to Group VIII noble metal preferably being between 0À1 to 1 and 2 to 1; an acidic catalyst may contain from 0À1 to 3 weight per cent of halogen, for example fluorine or chlorine, which may be derived by use of a halogen-containing Group VIII noble metal compound, for example chloroplatinic acid, in the preparation of the catalyst. Catalyst deactivated by use in hydrocarbon conversion may be regenerated by heating initially in a gas comprising oxygen at a temperature not exceeding 550‹ C. and thereafter in a gas comprising hydrogen at a temperature between 300 and 550‹ C. The specification gives details relating to preferred reaction conditions for dehydrocyclization, for example of light hydrocarbon oil to improve the octane rating thereof and of hydrocarbon oil comprising C 6 -C 10 paraffinic hydrocarbons to enhance the aromatic content thereof, and for reforming, for example of light hydrocarbon oil, such as a naphtha fraction boiling below 290‹ C. and preferably in the 65-230‹ C. range, to improve the octane rating thereof. As exemplified, dehydrocyclization of n-hexane to benzene is effected in the presence of a fixed bed of (a) Pt-Sn-Al 2 O 3 catalyst prepared by a procedure wherein non-acidic alumina is impregnated with an aqueous solution containing tin tartrate, dried at 120‹ C., calcined in air at 500‹ C., impregnated with an aqueous solution containing (NH 3 ) 4 Pt(OH) 2 and tin tartrate, dried at 120‹ C, calcined in air initially at 80‹ C. and subsequently at 500‹ C., and heated in hydrogen at 400‹ C. and (b) such catalyst after deactivation and subsequent regeneration thereof by heating initially in nitrogen containing 0À5 volume per cent oxygen at 350-380‹ C., then in air at 400‹C. and finally in hydrogen at 400‹ C. Reference is made to the use in dehydrocyclization of catalyst comprising non-acidic alumina, platinum and tin wherein the tin constitutes 20-70 atom per cent of the platinum and tin applied to the carrier, to the use in reforming of catalyst comprising acidic alumina, platinum and rhenium and also to the unspecified use of catalyst comprising platinum, rhenium and tin wherein the tin is derived from compositing with the carrier material and the rhenium is derived by application to the carrier.