Processes and systems for converting an oxygenate feedstock to a hydrocarbon product, selectivated catalysts and processes for reducing off-spec gasoline production during start-up are provided herein.

The present invention provides a modified composite molecular sieve, and a preparation method and an application of the modified composite molecular sieve. The modified composite molecular sieve comprises SiO.sub.2 and a composite molecular sieve that comprises molecular sieve MCM-22 and zeolite A selected from at least one of ZSM-22, ZSM-23 and ZSM-48, wherein, the molecular sieve MCM-22 covers around the zeolite A. The present invention further provides a catalyst and an application of the catalyst. The catalyst comprises a carrier and a noble metal loaded on the carrier, wherein, the carrier comprises a modified composite molecular sieve that is the modified composite molecular sieve provided in the present invention or the modified composite molecular sieve obtained with the method provided in the present invention. The catalyst that utilizes the composite molecular sieve as a carrier not only can decrease the solidifying point of waxy raw oil, but also can improve the yield of liquid product, is especially applicable to the isomerization dewaxing process of lube distillate, and has an advantage of remarkably improving the viscosity index of lube base oil.

Implementations of the disclosed subject matter provide a process for the aromatization of a methane-containing gas stream that includes contacting the methane-containing gas stream in a reaction zone of an aromatization reactor comprising an aromatization catalyst and a titanium alloy hydrogen acceptor under methane-containing gas aromatization conditions to produce a product stream comprising aromatics and hydrogen, wherein at least a portion of the produced hydrogen is bound by the titanium alloy hydrogen acceptor in the reaction zone and removed from the product and the reaction zone as titanium hydride, and wherein the titanium alloy hydrogen acceptor is a single phase alloy.

The invention relates to an olefin oligomerization process comprising the steps of: i) contacting a feed comprising olefins and nitriles with a guard bed comprising eta alumina; and ii) contacting the feed obtained in step i) with an oligomerization catalyst under conditions suitable to oligomerize the olefins in the feed. It also relates to the use of a guard bed comprising eta-alumina for reducing the content of basic organic compounds in a hydrocarbon feed.