An AFX framework type zeolite having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of greater than 50 is disclosed. The high-silica AFX framework type zeolite is synthesized from a reaction mixture having high silica and low hydroxide concentrations in the presence of an organic structure directing agent comprising 1,3-bis(1-adamantyl)imidazolium cations.

A method is disclosed for synthesizing molecular sieve SSZ-63 using 1-(decahydronaphthalen-2-yl)-1-methylpyrrolidinium cations as a structure directing agent.

A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index≤5, and the alkylation conditions comprise a temperature less than 500° C. Paraxylene may then be recovered from the alkylated aromatic product.

A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index≤5, and the alkylation conditions comprise a temperature less than 500° C. Paraxylene may then be recovered from the alkylated aromatic product.

A method for preparing a molecular sieve SCR (selective catalytic reduction) catalyst and a prepared catalyst therethrough. In the method, several molecular sieves are mixed and modified by transition metal or rare-earth metal via ion exchange, then loaded Fe by equivalent-volume impregnation, and loaded Cu by one or more liquid ion exchange. This present invention, combined with several techniques, such as modification of stable molecular sieve by transition and rare-earth metal, Fe loading by equivalent-volume impregnation and Cu loading by one or more liquid ion exchange, and after through stable and effective modification and loading control, the obtained catalyst material is coated on a carrier substrate via size mixing and coating process to be prepared into an integral catalyst.

A process the dehydration of methanol to dimethyl ether in the presence of a solid Brønsted acid catalyst selected from aluminosilicate zeolites which have a maximum free sphere diameter of greater than 3.67 Angstroms and heteropolyacids and a promoter selected from methyl formate, dimethyl oxalate and dimethyl malonate and the molar ratio of promoter to methanol is maintained at less than 1.

A new family of highly charged crystalline microporous metallophosphate molecular sieves has been synthesized. These metallophosphates are represented by the empirical formula of:

R.sup.p+.sub.rA.sup.+.sub.mM.sup.2+.sub.xE.sub.yPO.sub.z

where A is an alkali metal cation, R is at least one quaternary organoammonium cation, M is a divalent metal such as zinc and E is a trivalent framework element such as aluminum or gallium. This family of high charge density metallophosphate materials are among the first metalloalumino(gallo)phosphate-type molecular sieves to be stabilized by combinations of alkali and quaternary organoammonium cations, enabling unique compositions. This family of high charge density metallophosphate molecular sieves has catalytic properties for carrying out various hydrocarbon conversion processes and separation properties for separating at least one component.

A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index≤5, and the alkylation conditions comprise a temperature less than 500° C. The alkylation catalyst may be selectivated to produce a higher than equilibrium amount of paraxylene by using a molar ratio of alkylating agent to aromatic of at least 1:4.

A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index≤5, and the alkylation conditions comprise a temperature less than 500° C. The alkylation catalyst may be selectivated to produce a higher than equilibrium amount of paraxylene by using a molar ratio of alkylating agent to aromatic of at least 1:4.

Methods are provided for formulation of catalysts with improved catalyst exposure lifetimes under oxygenate conversion conditions. In various additional aspects, methods are described for performing oxygenate conversion reactions using such catalysts with improved catalyst exposure lifetimes. The catalyst formulation methods can include formulation of oxygenate conversion catalysts with binders that are selected from binders having a surface area of roughly 250 m.sup.2/g or less, or 200 m.sup.2/g or less. In various aspects, during formulation, a weak base can be added to the zeotype crystals, to the binder material, or to the mixture of the zeotype and the binder. It has been unexpectedly discovered that addition of a weak base, so that the weak base is present in at least one component of the binder mixture prior to formulation, can result in longer catalyst exposure lifetimes under methanol conversion conditions.