A molecular sieve has a silica/alumina molar ratio of 100-300, and has a mesopore structure. One closed hysteresis loop appears in the range of P/P.sub.0=0.4-0.99 in the low temperature nitrogen gas adsorption-desorption curve, and the starting location of the closed hysteresis loop is in the range of P/P.sub.0=0.4-0.7. The catalyst formed from the molecular sieve as a solid acid not only has a good capacity of isomerization to reduce the freezing point, but also can produce a high yield of the product with a lower pour point. The process for preparing the catalyst involves steps including crystallization, filtration, calcination, and hydrothermal treatment.

A method for preparing liquid fuel by direct conversion of syngas uses the syngas as reaction raw material and conducts a catalytic conversion reaction on a fixed bed or a moving bed. The catalyst is a composite catalyst formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of the component I is a metal oxide, and the component II is at least one of zeolites with one-dimensional ten-membered ring porous channels; and a weight ratio of the active ingredient in the component I to that in the component II is 0.1-20. The reaction process has high product yield and selectivity. The selectivity for liquid fuel composed of C.sub.5-C.sub.11 can reach 50-80%. The selectivity for aromatic hydrocarbon is less than 40% in C.sub.5-C.sub.11, while the selectivity for methane side product is less than 15%.

A process for olefin oligomerization can include: contacting a feedstock comprising at least one C.sub.3 to C.sub.20 olefin/paraffin under oligomerization conditions in the presence of a Si/Al ZSM-23 catalyst having no amine treatment and a Si/Al.sub.2 molar ratio of 20 to 60 and/or a Si/Al/Ti ZSM-23 catalyst having no amine treatment, a Si/Al.sub.2 molar ratio of 20 to 60, and a Ti/Al molar ratio of 0.1 to 3; and recovering an oligomeric product comprising dimers having a branching index of less than 2.1, trimers having a branching index of less than 2.1, and tetramers having a branching index of less than 2.1.

A process for olefin oligomerization can include: contacting a feedstock comprising at least one C.sub.3 to C.sub.20 olefin/paraffin under oligomerization conditions in the presence of a Si/Al ZSM-23 catalyst having no amine treatment and a Si/Al.sub.2 molar ratio of 20 to 60 and/or a Si/Al/Ti ZSM-23 catalyst having no amine treatment, a Si/Al.sub.2 molar ratio of 20 to 60, and a Ti/Al molar ratio of 0.1 to 3; and recovering an oligomeric product comprising dimers having a branching index of less than 2.1, trimers having a branching index of less than 2.1, and tetramers having a branching index of less than 2.1.

A process for olefin oligomerization can include contacting a feedstock comprising C.sub.n and C.sub.2n olefins/paraffins under oligomerization conditions in the presence of an oligomerization catalyst, wherein n is 2 to 15; and recovering an oligomeric product comprising C.sub.3n oligomers having a branching index of less than 2.1. Optionally, the feedstock can further comprise C.sub.3n olefins/paraffins.

A catalyst for the carbonylation of dimethyl ether to methyl acetate. The catalyst comprises a zeolite, such as a mordenite zeolite, at least one Group IB metal, such as copper, and/or at least one Group VIII metal, such as iron, and at least one Group IIB metal, such as zinc. Such a catalyst with combined metals provides enhanced catalytic activity, improved stability, and improved selectivity to methyl acetate, and does not require a halogen promoter, as compared to a metal-free or copper only zeolite.

A molecular sieve has a silica/alumina molar ratio of 100-300, and has a mesopore structure. One closed hysteresis loop appears in the range of P/P.sub.0=0.4-0.99 in the low temperature nitrogen gas adsorption-desorption curve, and the starting location of the closed hysteresis loop is in the range of P/P.sub.0=0.4-0.7. The catalyst formed from the molecular sieve as a solid acid not only has a good capacity of isomerization to reduce the freezing point, but also can produce a high yield of the product with a lower pour point. The process for preparing the catalyst involves steps including crystallization, filtration, calcination, and hydrothermal treatment.

A catalyst for the carbonylation of dimethyl ether to methyl acetate. The catalyst comprises a zeolite, such as a mordenite zeolite, at least one Group IB metal, such as copper, and/or at least one Group VIII metal, such as iron, and at least one Group IIB metal, such as zinc. Such a catalyst with combined metals provides enhanced catalytic activity, improved stability, and improved selectivity to methyl acetate, and does not require a halogen promoter, as compared to a metal-free or copper only zeolite.

A catalyst for the carbonylation of dimethyl ether to methyl acetate. The catalyst comprises a zeolite, such as a mordenite zeolite, at least one Group IB metal, such as copper, and/or at least one Group VIII metal, such as iron, and at least one Group IIB metal, such as zinc. Such a catalyst with combined metals provides enhanced catalytic activity, improved stability, and improved selectivity to methyl acetate, and does not require a halogen promoter, as compared to a metal-free or copper only zeolite.

A process for olefin oligomerization can include contacting a feedstock comprising C.sub.n and C.sub.2n olefins/paraffins under oligomerization conditions in the presence of an oligomerization catalyst, wherein n is 2 to 15; and recovering an oligomeric product comprising C.sub.3n oligomers having a branching index of less than 2.1. Optionally, the feedstock can further comprise C.sub.3n olefins/paraffins.