The present invention relates to a process for the dimerization of alkenes comprising (1) providing a gas stream comprising one or more alkenes; and (2) contacting the gas stream provided in (1) with a catalyst for obtaining a mixture M1 comprising one or more dimerization products of the one or more alkenes, wherein the catalyst in (2) comprises a zeolitic material having a framework structure type selected from the group consisting of MOR, BEA, FER, MFI, TON, FAU, and mixtures of two or more thereof, wherein the framework structure of the zeolitic material comprises YO.sub.2, wherein Y stands for one or more tetravalent elements.

According to one or more embodiments of the present disclosure, chemical streams may be processed by a method which may comprise operating a first chemical process, stopping the first chemical process and removing the first catalyst from the reactor, and operating a second chemical process. The reaction of the first chemical process may be a dehydrogenation reaction, a cracking reaction, a dehydration reaction, or a methanol-to-olefin reaction. The reaction of the second chemical process may be a dehydrogenation reaction, a cracking reaction, a dehydration reaction, or a methanol-to-olefin reaction. The first reaction and the second reaction may be different types of reactions.

Methods for cracking a hydrocarbon feed stream include contacting a hydrocarbon feed stream with a catalyst system in a catalytic cracking unit having a flowing gas stream to obtain a cracking product containing light olefins. The catalyst system includes at least a base catalyst. The base catalyst includes a pentasil zeolite. The pentasil zeolite includes from 0.01% to 5% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite. The flowing gas stream comprises hydrogen and, optionally, at least one additional carrier gas.

A system and a method are provided for producing aromatics. Such a system includes a cracker unit configured to convert a light alkane into an olefin-containing hydrocarbon comprising at least one alkene, and an aromatization unit. The light alkane is selected from the group consisting of methane, ethane, propane, butane, and a combination thereof. The cracker unit is configured to at least partially feed the olefin-containing hydrocarbon into the aromatization unit. Such an olefin-containing hydrocarbon comprises at least 40 wt. % of the at least one alkene. The aromatization unit is used to convert the olefin-containing hydrocarbon therein into a product stream, which includes an aromatic hydrocarbon selected from the group consisting of benzene, toluene, xylenes, and a combination thereof.

The present invention relates to the field of alkylation catalysts, and disclosed are a composite ZSM-5 molecular sieve, a preparation method therefor, a catalyst and an application thereof. A single crystal of the composite ZSM-5 molecular sieve comprises a main crystal and a twin crystal; the main crystal and the twin crystal are both ZSM-5 crystals; a crystal plane [010] of the main crystal is covered by a crystal plane [100] of the twin crystal; and the ratio of the number of sinusoidal pore openings to the number of straight pore openings on the outer surface of the single crystal of the composite ZSM-5 molecular sieve is (0.7-10:1), and the molar ratio Y1 of an Si element to an Al element within 10 nm of the surface is (300-2000):1. The single crystal of the composite ZSM-5 molecular sieve of the present invention has a large ratio of the number of sinusoidal pore openings to the number of straight pore openings, and is aluminum-poor on the surface and aluminum-rich on the inside. When applied to the toluene methanol alkylation reaction to prepare p-xylene, the selectivity of p-xylene may be greatly improved.

A process and system for the conversion of a feedstock comprising C3-C5 light alkanes to a C5+ hydrocarbon product, for example, a BTX-rich hydrocarbon product, by performing the alkane activation (first-stage) and the oligomerization/aromatization (second-stage) in separate stages, which allows each conversion process to occur at optimal reaction conditions thus increasing the overall hydrocarbon product yield. The alkane activation or first-stage is operated at a higher temperature than the second-stage since light alkanes are much less reactive than light olefins. Since aromatization of olefins is more efficient at higher pressure, the second-stage is maintained at a higher pressure than the first-stage. Further, fixed-bed catalysts are used in each of the first-stage and the second-stage.

A method for preparing a zeolite catalyst for catalytic cracking of hydrocarbons to produce propylene is provided, which specifically includes steps of mixing a silicon source, a templating agent, an aluminium source, and a solvent to form a zeolite precursor solution, which is then subjected to hydrothermal crystallization, washing, drying, and calcination to obtain a zeolite precursor; ion-exchanging the zeolite precursor with ammonium ions, followed by drying and calcination; and loading aluminum onto the ion-exchanged zeolite precursor as a carrier via incipient-wetness impregnation by using an aluminium-containing solution, followed by drying and calcination. Zeolite catalysts prepared by the method and use of the catalysts in catalytic cracking of hydrocarbons to produce propylene are also provided.

The present disclosure provides systems and methods for producing aromatic compounds in high yield from a mixed aromatic feed stream. Also disclosed are systems and methods for producing aromatic compounds in high yield from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like.

Disclosed is a method for converting cymene generated from renewable low value terpene streams into renewable benzene, toluene, xylenes, and cymene isomers (ortho and meta) under flow disproportionation reaction conditions, which compounds are basic building blocks for fragrance materials. This technology has potential to replace high volume petrochemical-based feedstocks with plant-based building blocks that can fill the renewability gap for key fragrance ingredients.

Processes for converting one or more C.sub.1-C.sub.5 linear or branched alcohols to one or more C.sub.2-C.sub.5 olefins are provided. In one exemplary embodiment, the process can be a single stage process for the direct conversion of C.sub.1-C.sub.5 alcohols to olefinic mixtures (e.g., C.sub.2-C.sub.5) carried out in a reactor using a catalyst that includes zeolite doped with boron and phosphor. Systems for carrying out these processes are also provided.