A ZSM-23 zeolite and a process for preparing the same and use thereof are provided. The total acid amount of the ZSM-23 zeolite is 0.05-0.25 mmol/g, preferably 0.06-0.22 mmol/g, more preferably 0.06-0.20 mmol/g. The strong acid content of the ZSM-23 zeolite is 5-33%, preferably 7-33%, more preferably 9-33%, or further preferably 7-31%, further more preferably 10-28% of the total acid amount. The strong acid refers to an acid having a desorption temperature of 350 C. or higher in an NH3 temperature programmed desorption (NH3-TPD). The ZSM-23 zeolite has a low strong acid content.

A ZSM-23 zeolite and a preparation process thereof are provided. The pore volume of mesopores having a pore size of 3-8 nm of the zeolite is 45-90% of the total pore volume of the zeolite. The zeolite has a relative crystallinity of 95-120% and a relative crystallinity retention of 95-100% after a hydrothermal treatment with steam for 2 hours at 600 C. The process for preparing the zeolite includes the following steps: (1) preparing or selecting a silicon source for preparing the ZSM-23 zeolite, such as amorphous silica; (2) performing an alkali treatment on the silicon source for preparing the ZSM-23 zeolite such as amorphous silica mentioned in step (1); and (3) preparing the ZSM-23 zeolite by using the alkali-treated amorphous silica as the silicon source. The ZSM-23 zeolite has a rich mesoporous structure and a good hydrothermal stability.

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 method to make a phosphorus modified zeolite can include providing a zeolite having at least one ten member ring, making an ion-exchange, steaming the zeolite, and introducing phosphorus on the zeolite. The zeolite can be mixed with one or more binders and shaping additives, and then shaped. A metal can be introduced, and the catalyst can be washed, calcined, and steamed in an equilibration step. The steaming can be at performed at a steam severity (X) of at least about 2. The steaming can be performed at a temperature above 625 C. The catalyst can be used in alcohol dehydration, olefin cracking, MTO processes, and alkylation of aromatics by alcohols with olefins and/or alcohols.

A method for preparing aromatic hydrocarbons with carbon dioxide hydrogenation, comprising: directly converting a mixed gas consisting of carbon dioxide and hydrogen with the catalysis of a composite catalyst under reaction conditions of a temperature of 250-450 C., a pressure of 0.01-10.0 MPa, a feedstock gas hourly space velocity of 500-50000 mL/(h.Math.g.sub.cat) and a H.sub.2/CO.sub.2 molar ratio of 0.5-8.0, to produce aromatic hydrocarbons. The composite catalyst is a mixture of a first component and a second component. The first component is an iron-based catalyst for making low-carbon olefin via carbon dioxide hydrogenation, and the second component is at least one of metal modified or non-modified molecular sieves which are mainly used for olefin aromatization. In the method, CO.sub.2 conversion per pass may be above 33%, the hydrocarbon product selectivity may be controlled to be above 80%, the methane content is lower than 8%, C.sub.5+ hydrocarbon content is higher than 65% and the proportion of the aromatic hydrocarbons in C.sub.5+ hydrocarbons may be above 63%.

The present invention relates to a process for producing aromatics, a process for producing p-xylene and terephthalic acid, and a device for producing aromatics. The process for producing aromatics at least comprises a step of producing C8 olefin from a compound having a lactone group and a step of producing aromatics from the C8 olefin. The process for producing aromatics has the characters of high yield of aromatics and high selectivity to xylene.

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 crystalline molecular sieve selected from at least one of ZSM-22, ZSM-23 and ZSM-48, wherein, the molecular sieve MCM-22 covers around the crystalline molecular sieve. 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.

The present application pertains to family of new crystalline molecular sieves designated SSZ-93. Molecular sieve SSZ-93 is structurally similar to sieves falling within the MTT structure type such as SSZ-32x, SSZ-32, ZSM-23, EU-13, ISI-4, and KZ-1 family of molecular sieves. SSZ-93 is characterized as having magnesium.

The invention relates to a process for dehydration of a mono-alcohol, or of a mixture of at least two mono-alcohols, having at least 2 carbon atoms and at most 7 carbon atoms into olefins having the same number of carbons, wherein the process uses a catalyst composition that comprises a modified crystalline aluminosilicate has an acidity between 350 and 500 mol/g that comprises, and further wherein the catalyst composition is obtained by a process comprising the steps of providing a crystalline aluminosilicate having a Si/Al framework molar ratio greater than 10; and steaming said crystalline aluminosilicate, or said shaped and/or calcined crystalline aluminosilicate at a temperature ranging from 100 C. to 380 C.; and under a gas phase atmosphere, without liquid, containing from 5 wt % to 100 wt % of steam; at a pressure ranging from 2 to 200 bars; at a partial pressure of H.sub.2O from 2 bars to 200 bars; and said steaming being performed during at least 30 min and up to 144 h.

The present invention relates to a process for producing aromatics, p-xylene and terephthalic acid. The process for producing aromatics comprises a step of contacting an oxygen-containing raw material with an aromatization catalyst, under aromatization reaction conditions, to produce aromatics. The process for producing aromatics has an advantage of high yield of carbon as aromatics.