Processes for converting C8 aromatic hydrocarbons. In some embodiments, the process can include feeding a gaseous hydrocarbon feed that can include meta-xylene, ortho-xylene, or both into a conversion zone. The process can also include contacting the gaseous hydrocarbon feed with a catalyst that can include a ZSM-11 zeolite in the conversion zone under conversion conditions to effect isomerization of at least a portion of any meta-xylene, or at least a portion of any ortho-xylene, or both to produce a conversion product rich in para-xylene. In some embodiments, the ZSM-11 zeolite can have an alpha value of 1 to 3,000 and a molar ratio of silica to alumina of from 15 to 200.

Processes for converting C8 aromatic hydrocarbons. In some embodiments, the process can include feeding a gaseous hydrocarbon feed that can include meta-xylene, ortho-xylene, or both into a conversion zone. The process can also include contacting the gaseous hydrocarbon feed with a catalyst that can include a ZSM-11 zeolite in the conversion zone under conversion conditions to effect isomerization of at least a portion of any meta-xylene, or at least a portion of any ortho-xylene, or both to produce a conversion product rich in para-xylene. In some embodiments, the ZSM-11 zeolite can have an alpha value of 1 to 3,000 and a molar ratio of silica to alumina of from 15 to 200.

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 is disclosed for producing small crystal, high aluminum content zincoaluminosilicate crystalline materials having the SSZ-41 framework structure. The compositions made according to that method, as well as uses of the same, are also disclosed.

Disclosed are a catalyst and a preparation method therefor, the catalyst being able to maintain a high production yield of C8 aromatic hydrocarbons in the process of converting a feedstock containing alkyl aromatics to C8 aromatic hydrocarbons such as mixed xylene through disproportionation/transalkylation/dealkylation while reducing a content of ethylbenzene in the products.

The invention relates to a p-xylene separation process wherein at least a portion of ethylbenzene present in an aromatics-containing feed is removed prior to isomerization. Aspects of the invention provide a process for producing p-xylene. The process includes providing a first mixture comprising ≧5.0 wt. % of aromatic C.sub.8 isomers, the C.sub.8 isomers comprising p-xylene and ethylbenzene. A p-xylene-containing portion and an ethylbenzene-containing portion are separated from the first mixture in a first separation stage to form a p-xylene-depleted raffinate. The first separation stage can include at least one simulated moving-bed adsorptive separation stage. At least a portion the p-xylene-depleted raffinate in the liquid phase is reacted to produce a reactor effluent comprising aromatic C.sub.8 isomers. The first mixture can be combined with ≧50.0 wt. % of the reactor effluent's aromatic C.sub.8 isomers. The combining can be carried out before and/or during the separating of the p-xylene and ethylbenzene portions.

Processes for activating precious metal-containing catalysts. The processes can decrease the amount of high purity hydrogen required for starting up a catalytic conversion process such as transalkylation of heavy aromatics, without detrimental impact to the metal activity. The processes can include a low temperature treatment step with a high purity first gas, such as hydrogen generated by electrolysis and/or reformer hydrogen diluted with high purity inert gas, and a high temperature treatment step with a low purity second gas such as the reformer hydrogen. Also, the processes can include mixing a hydrogen gas of high or low purity with a high purity inert gas to form a gas mixture with a proportion of hydrogen no less than 2% and a reduced carbon monoxide concentration relative to the low purity hydrogen, and contacting the catalyst with the gas mixture.

Disclosed are a catalyst and a preparation method therefor, the catalyst being able to maintain a high production yield of C8 aromatic hydrocarbons in the process of converting a feedstock containing alkyl aromatics to C8 aromatic hydrocarbons such as mixed xylene through disproportionation/transalkylation/dealkylation while reducing a content of ethylbenzene in the products.

Hydrocarbon composition plays vital role in fuel quality. For gasoline/motor spirit applications the hydrocarbon should have more octane-possessing molecules from the groups of aromatics, naphthenics and isoparaffins, while n-paraffins are not preferred due to their poor octane. Among the high-octane groups, again aromatics occupy the top but not more than 35 vol % aromatics can be mixed in gasoline for engine applications to avoid harmful emission, But there is no single process that addresses so far the issue of co-producing all the desired hydrocarbon components in a single process. Thus, it is interesting to have a single once-through process working on single catalyst system to produce mixture of all three high-octane molecules namely, aromatics, naphthenics and isoparaffins directly from low-value, low-octane n-paraffin feed. Herein, we report a novel single-step catalytic process for the simultaneous production of aromatics, naphthenics and isoparaffins for gasoline and petrochemical applications.

A method is provided for synthesizing molecular sieves of SZR framework type using 1,2,3-trimethylimidazolium cations as a structure directing agent and alumina-coated silica as a combined source of silicon and aluminum.