Patent GB-667876-A (GB)
Title: Improvements in or relating to dehydrogenation and cracking catalysts
IPC: B01J37/00
Filed: 1950-02-02
Abstract: Styrene is prepared by the dehydrogenation of ethylbenzene in the presence of a catalyst formed by mixing the normal catalyst yielding substances and a cementitious binder with from 3-15 per cent (preferably 7-15 per cent) by weight, based on the weight of the total dry solids, of a powdered methyl cellulose whose 2 per cent solution in water at 20 DEG  C. has a viscosity of 300-7500 (preferably 2000-3000) centipoises, and with enough water to make a thick paste, forming the paste into pellets, dehydrating the pellets, and heating then to at least the normal temperature for the dehydrogenation to decompose the methyl cellulose and to activate the catalyst.  Catalysts are prepared from mixtures containing potassium dichromate, potassium carbonate, ferric oxide, zinc oxide, aluminium oxide, calcium oxide, potassium hydroxide, chromic oxide, and graphite (or carbon black) (see Group III).  Ethylbenzene mixed with steam is passed over the pellets in a tube at 650 DEG  C. and the temperature is gradually lowered.  A 40 per cent conversion to styrene is obtained in a single pass at 610-615 DEG  C., i.e. 15-20 DEG  C. lower than with a catalyst prepared without using methyl cellulose; at a given temperature the yield of styrene is higher.ALSO:A dehydrogenation or cracking catalyst of increased strength and porosity and improved activity is prepared by mixing the normal catalyst yielding substances and a cementitious binder with from 3-15 per cent (preferably 7-15 per cent) by weight, based on the weight of the total dry solids, of a powdered methyl cellulose whose 2 per cent solution in water at 20 DEG C. has a viscosity from 300-7500 (preferably 2000-3000) centipoises, and with enough water to make a thick paste, forming the paste into pellets, dehydrating the pellets, and heating them to at least the normal temperature for the intended reaction to decompose the methyl cellulose and to activate the catalyst.  The paste may be extruded as rods, and the rods cut into pellets; the pellets may be ground for use in fluid or moving beds.  Catalysts for use in the dehydrogenation of ethylbenzene to styrene are prepared from a paste containing aqueous solutions of potassium carbonate and potassium dichromate, ferric oxide, a slow-setting corrosion resistant refractory cement (containing Al2O3 and CaO), graphite, and methyl cellulose; carbon black may replace the graphite.  After drying and heating at 600-650 DEG C. in a stream of steam and ethylbenzene, the catalysts are found to give higher yields of styrene at a given temperature, or to effect the same rate of conversion at a lower temperature, as compared with similar catalysts prepared without using methyl cellulose (see Group IVb). Another catalyst for the dehydrogenation of ethylbenzene is prepared from a paste containing zinc oxide, aluminium oxide, calcium oxide, potassium hydroxide, chromic oxide, cement binder, and methyl cellulose. Catalysts for the dehydrogenation of paraffin hydrocarbons, cycloparaffins, heterocyclic compounds, alcohols, and polynuclear hydro-aromatic hydrocarbons may also be prepared.