28820 results about "Molecular sieve" patented technology

The invention discloses a catalyst modification method for preparing methyl acetate by carbonylating dimethyl ether. The method is applied to the reaction process in which the dimethyl ether reacts with the carbon monoxide to high selectively form methyl acetate in the presence of an acid molecular sieve catalyst, particularly a mordenite molecular sieve. Pyridine organic amines are utilized to modify the mordenite molecular sieve and modify a channel structure and the acidity of the molecular sieve, thereby effectively inhibiting carbon deposition and greatly improving the stability of catalysts. The use of the catalysts by the method can catalyze the carbonylation of dimethyl ether to obtain methyl acetate under mild conditions. The conversion rate of dimethyl ether is between 10 and 60percent, the selectivity of the methyl acetate is over 99 percent, and the activity of the catalysts is kept steady after the reaction is performed for 48 hours.

The ability to design and construct solid-state materials with pre-determined structures is a grand challenge in chemistry. An inventive strategy based on reticulating metal ions and organic carboxylate links into extended networks has been advanced to a point that has allowed the design of porous structures in which pore size and functionality can be varied systematically. MOF-5, a prototype of a new class of porous materials and one that is constructed from octahedral Zn—O—C clusters and benzene links, was used to demonstrate that its 3-D porous system can be functionalized with the organic groups, —Br, —NH2, —OC3H7, —OC5H11, —H4C2, and —H4C4, and its pore size expanded with the long molecular struts biphenyl, tetrahydropyrene, pyrene, and terphenyl. The ability to direct the formation of the octahedral clusters in the presence of a desired carboxylate link is an essential feature of this strategy, which resulted in the design of an isoreticular (having the same framework topology) series of sixteen well-defined materials whose crystals have open space representing up to 91.1% of the crystal volume, and homogeneous periodic pores that can be incrementally varied from 3.8 to 28.8 angstroms. Unlike the unpredictable nature of zeolite and other molecular sieve syntheses, the deliberate control exercised at the molecular level in the design of these crystals is expected to have tremendous implications on materials properties and future technologies. Indeed, data indicate that members of this series represent the first monocrystalline mesoporous organic / inorganic frameworks, and exhibit the highest capacity for methane storage (155 cm3 / cm3 at 36 atm) and the lowest densities (0.41 to 0.21 g / cm3) attained to date for any crystalline material at room temperature.

The invention relates to a process for preparing arene selectivity by enhancing methanol aromatizatian. The process uses methanol as raw material, compositely modifies HZSM-5 molecular sieve catalyst by active ions like Ga, Zn, Cu, Cr and Ag for catalyzing methanol aromatizatian, employs the fixed bed continuous process or the floating bed continuous process, wherein the reaction pressure is 0.1-3.5MPa; the reaction temperature is 380-500 DEG C; the space velocity of raw material liquid is 0.1-10.0 h; and N2 space velocity is 120-800 h. The advantages of the invention lie in collocation combination of mixing ion modification, and arene selectivity reaches to 70%.

The present invention provides a hydrocracking catalyst having high activity, high medium oil selectivity, catalyst constitute uses amorphous silica-alumina as a carrier, Y type molecular sieve processed by special modification is an acidity component, the molecular sieve has a high crystallinity and a lower cell parameter, a plenty quadric hole, larger surface, in addition, has a small acid center, even distribution, no strong acid center, 70-80% is moderate intensity acid center, 20-30% is weak acid center, and the molecular sieve also has a strong anti-nitrogen ability and better damaging ability, the hydrocracking catalyst using the molecular sieve has a better hydrocracking activity, and a higher medium oil selectivity, and a strong anti-nitrogen ability at the same time. The invention uses heavy hydrocarbon single stage or single stage serial hydrocracking process generate midbarrel oil product, and has better activity and medium oil selectivity.

A composite molecular sieve with TON and MFI structures is prepared in static crystallizing condition. In the procedure of preparing gel, less crystal seeds and salt are added. The Si / Al ratio on its crystal lattice is greater than 50.

The invention discloses a method for preparing aromatic hydrocarbons and propylene simultaneously employing methanol / dimethyl ether, comprising the following steps: 1) placing raw materials containing methanol or / and dimethyl ether, metals and molecular sieve based catalyst which is modified through silanizing in a first fixed bed reactor to perform catalytic reaction; 2) separating the products obtained in step 1) to obtain propylene, then placing propylene in a second fixed bed reactor with molecular sieve based catalyst which is modified by using metals to react, then performing aromatization on the obtained product in step 1) and obtaining aromatic hydrocarbons; then separating to obtain toluene and sending toluene back to the outlet of the first fixed bed reactor as a raw material. In the method, methanol is converted and prepared to aromatic hydrocarbons while propylene is produced at the same time and the content of paraxylene in aromatic hydrocarbons is high. In the products prepared by the method, the content of propylene can reach above 20%, the content of aromatic hydrocarbons can reach above 58wt% and the content of paraxylene in aromatic hydrocarbons is more than 35wt%.

At lower temperatures an acidic molecular sieve adsorbent preferentially adsorbs water and basic organic nitrogen compounds over weakly basic organic nitrogen compounds such as nitrites. Elevated temperatures improve the capacity of acidic molecular sieve adsorbents to adsorb nitrites in the presence of water.

A system for reducing ammonia (NH3) emissions includes (a) a first component comprising a first substrate containing a three-way catalyst, wherein the first component is disposed upstream of a second component comprising a second substrate containing an ammonia oxidation catalyst, wherein said ammonia oxidation catalyst comprises a small pore molecular sieve supporting at least one transition metal; and (b) an oxygen-containing gas input disposed between the components. For example, a CHA Framework Type small pore molecular sieve may be used. A method for reducing NH3 emission includes introducing an oxygen-containing gas into a gas stream to produce an oxygenated gas stream; and exposing the oxygenated gas stream to an NH3 oxidation catalyst to selectively oxidize at least a portion of the NH3 to N2.