Acidic Cs{sup +}, NH{sub 4}{sup +}, and K{sup +} salts of 12-tungstophosphoric acid as solid catalysts for isobutane/2-butene alkylation

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0398· OSTI ID:468693

Corma, A; Martinez, A; Martinez, C ^[1]

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1. Universidad Politecnica de Valencia (Spain)

The cesium, ammonium, and potassium salts of 12-tungstophosphoric acid (HPW) have been prepared with different stoichiometries (1{le}x{le}3) and their catalytic behavior measured for the liquid phase alkylation of isobutane with 2-butene at 80{degrees}C. The salts with a cation content of 2.5 {le}x{le}3, and that of Cs{sup +} with x=2, showed a much higher surface area than the parent acid, which is partially due to the formation of micropores. The micropores presented a fairly homogeneous distribution, with an average diameter in the range of 6-11 {Angstrom}, depending on the type of cation and cation content. The activity of the heteropoly acid and their monovalent type B salts for isobutane alkylation could be correlated with the surface acidity of the solids. Thus, the initial (1 min TOS) olefin conversion went through a maximum for the NH{sub 4}{sup +} and K{sup +} salts with a cation content of x = 2.5, and in the range of 2{le}x{le}2.5 in the case of the Cs{sup +} compounds. (NH{sub 4}){sup 2.5}PW showed a very high initial cracking activity (ca. 72 wt% C{sub 5}-C{sub 7} in C{sub 5+}), suggesting the presence of surface acid sites of a higher acid strength in the ammonium salt, as compared to the caesium and potassium salts with similar composition. In all cases the desired trimethylpentanes (TMPs) were the predominant compounds in the C{sub 8} fraction formed in the initial reaction stages. The deactivation rate also depended on the nature of the cation exchanged in the heteropoly salts. 57 refs., 7 figs., 4 tabs.

• OSTI ID: 468693
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 164; ISSN JCTLA5; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
10 SYNTHETIC FUELS
40 CHEMISTRY
ALKYLATION
AMMONIUM COMPOUNDS
BUTANE
BUTENES
CATALYTIC CRACKING
CATALYTIC EFFECTS
CESIUM COMPOUNDS
CHEMICAL REACTION KINETICS
HETEROGENEOUS CATALYSIS
POTASSIUM COMPOUNDS
STOICHIOMETRY
SURFACE AREA
TUNGSTOPHOSPHATES