Exxon Research and Engineering Company

Exxon Chemical Patents, Inc.

Wicher T Koetsier

Johannes P Verduijn

Cornelis B De Gruijter

Mechilium J Janssen

Cornelis W Van Oorschot

Zeolite L in very small crystalline form is prepared by a process in which an alkaline reaction mixture comprising water, a source of silicon (SiO.sub.2), a source of alkali metal (M) (KOH) and a source of aluminium (Al.sub.2 O.sub.3.3H.sub.2 O) or gallium is heated to a temperature of at least 80.degree. C. for a period of time long enough to form zeolite L, the composition of the reaction mixture having the following molar ratios (expressed as oxides):

Process for separating dimethylnaphthalene isomers with zeolite L

Zeolite L preparation

Zeolite L with cylindrical morphology and having excellent properties as a catalyst base may be prepared with high crystallinity and reduced contamination even in large scale syntheses were fluctuation in gel compositions may occur by employing a gel composition having the following molar ratios of components:

Hydrocarbon conversion processes which use catalyst compositions comprising a core of silica with an overlying modified-silica zeolite, preferably containing aluminium, gallium or boron, show improved catalytic activity. The composites are prepared by introducing preformed silica particles, preferably with a crystallite size greater than 0.1.mu., into a reaction mixture comprising a silicon source, a source of the modifying element, and preferably an organic template such as a tetraalkylammonium compound to form the modified-silica zeolite with a constraint index of from 1 to 12. The weight ratio of the silica core to SiO.sub.2 in the reaction mixture is preferably 1:1 to 10:1.

Hydrocarbon conversion process with a composite zeolite

Reduced downgrading in xylene isomerization of ethylbenzene-depleted feeds is achieved by carrying the process out over gallosilicate or borosilicate zeolites, preferably in the form of compositions comprising a core of catalytically-inactive crystalline silica with an overlying zeolite layer. The composites are prepared by introducing preformed silica particles, preferably with a crystallite size greater than 0.1.mu., into a reaction mixture comprising a silicon source, a source of the modifying element, and preferably an organic template such as a tetraalkylammonium compound. The weight ratio of the silica core to SiO.sub.2 in the reaction mixture is preferably 0.5:1 to 25:1.

Xylene isomerization

Catalyst compositions comprising a core of silica with an overlying modified-silica zeolite, preferably containing aluminium, gallium or boron, show improved catalytic activity. The composites are prepared by introducing preformed silica particles, preferably with a crystallite size greater than 0.1 .mu., into a reaction mixture comprising a silicon source, a source of the modifying element, and preferably an organic template such as a tetraalkylammonium compound to form the modified-silica zeolite with a constraint index of from 1 to 12. The weight ratio of the silica core to SiO.sub.2 in the reaction mixture is preferably 1:1 to 10:1.

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Mijnsheerenland, Netherlands

Wicher T Koetsier