Zeolite catalysts of improved activity and para-selectivity
AssigneeMobil Oil Corporation
InventorChin-Chiun Chu
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Abstract
A method is provided for treating modified ZSM-5 type zeolite catalysts with water vapor in order to enhance the aromatics conversion activity and/or the para-selective properties of such catalysts for the conversion of aromatic materials. The modified zeolites so treated are those which contain a minor proportion of a difficultly reducible oxide such as magnesium oxide, calcium oxide and/or phosphorus oxide. Such catalyst compositions can be used in alkylation, transalkylation or disproportionation processes to provide improved yields of alkylated aromatic product mixtures having exceptionally high concentrations of the para-dialkylbenzene isomer.
Claims12
A method for treating a chemically modified zeolite catalyst in order to enhance the aromatics conversion activity and/or the para-selectivity of said catalyst, said catalyst comprising both a crystalline zeolite material having a constraint index within the approximate range of 1 to 2 and a silica/alumina mole ratio of at least 12 and a minor proportion of one or more difficultly reducible oxides selected from the group consisting of oxides of the metals of Groups IA, IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIIB, IVB and VB of the Periodic Chart and combination of phosphorus oxide with one or more of said metal oxides, said method comprising the steps of:
- (i) contacting an inert inorganic gaseous diluent with liquid water, whereby said diluent becomes essentially saturated with water in the vapor state, and whereby water in the liquid state becomes dispersed in said diluent;
- (ii) converting essentially all of said liquid water dispersed in said diluent to water in the vapor state by increasing the temperature of the water-containing diluent of step (i) to a temperature sufficient to accomplish such conversion;
- and
- (iii) contacting said catalyst with said essentially liquid water-free diluent of step (i) at a temperature between about 40.degree. C. and 700.degree. C. for a period of from about 1 to 72 hours and at a rate of at least about 0.005 gram of water per gram of catalyst per hour.
A method for treating ZSM-5, said ZSM-5 comprising a minor proportion of one or more difficultly reducible oxides selected from the group consisting of oxides of the metals of Groups IA, IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIIB, IVB and VB of the Periodic Chart and combinations of phosphorus oxide with one or more of said metal oxides, said method comprising the steps of:
- (i) moistening air with water at ambient temperature;
- and
- (ii) passing said water moistened air of step (i) into a reactor containing said ZSM-5, said reactor being maintained at a temperature between about 40.degree. C. and 700.degree. C., for a period of from about 1 to 72 hours and at a rate of at least about 0.005 gram of water per gram of catalyst per hour, whereby said ZSM-5 is contacted with water vapor.
Dependencies are inferred from the claim text.