Showing papers on "Catalyst support published in 1989"

Silicon bridged transition metal compounds

Abstract: Silicon-bridged transition metal compounds and their use as α-olefin polymerization catalysts are disclosed. A chiral silicon-bridged metallocene catalyst polymerizes α-olefins to high isotacity with a minimum of inversions at high rates of catalyst activity. The catalyst is easily made in high yields and readily separated from atactic meso forms.

Method for utilizing triethylaluminum to prepare an alumoxane support for an active metallocene catalyst

Abstract: of EP0368644This invention relates to a process for preparing a supported metallocene alumoxane catalyst for use in the polymerization of olefins. The invention particularly relates to the use of silica gel containing from about 6 to about 20 per cent by weight adsorbed water as the catalyst support material. It has been found that such silica gel may be safely added to a solution, of trialkylaluminum to form by direct reaction with the adsorbed water content of the silica gel catalyst support material the majority of the alumoxane component requirement of the catalyst system. An alkylalumoxane coated silica gel is formed to which a trimethylaluminum treated metallocene may be added and the resulting material dried to free-flowing powder. The dry free flowing powder may then be used as a supported metallocene alumoxane catalyst complex for gas phase or liquid phase polymerization of olefins. The supported catalyst produced by such procedure has an activity at least comparable to a catalyst of similar composition which is produced exclusively with trimethylaluminum as the alumoxane forming aluminum alkyl.

Metal-support effects in Pt/L-zeolite catalysts

Abstract: A series of Pt/L-zeolites with different cations (varying acidity) were prepared and characterized by H2 and CO chemisorption and competitive toluene/benzene hydrogenation. The ratio of adsorption equilibrium constants for toluene/benzene was extracted from rates of hydrogenation. The variation of this ratio across a series of alkaline-earth exchanged Pt/L-zeolites indicates that there is a varying support interaction with Pt clusters in the zeolite and suggests that the clusters interact electronically with the support.

Upgrading naphtha in a multiple riser fluid catalytic cracking operation employing a catalyst mixture

Abstract: A catalytic cracking process is provided featuring multiple risers (26, 27) in which a variety of hydrocarbon conversion reactions take place, a stripping unit (36) in which entrained hydrocarbon material is removed from catalyst and a regeneration zone (2) in which spent cracking catalyst is regenerated which comprises: a) converting a relatively high boiling hydrocarbon charge material (30) in a first riser (27) in the presence of a first catalyst component which is an amorphous cracking catalyst and/or a large pore crystalline zeolite cracking catalyst to provide lighter products: b) converting an ethylene-rich charge material (88) introduced to a second riser (26) at a lower level thereof in the presence of a second catalyst component which is a shape selective medium pore crystalline silicate zeolite catalyst to provide heavier products and to increase the temperature of the catalyst in the region: and, c) converting a naphtha charge material (89) introduced to the second riser (26) at a higher level thereof in the presence of the second catalyst component to provide a relatively high octane gasoline product.

Molecular sieve-palladium-platinum catalyst on a substrate

Abstract: A catalyst system for the oxidation of hydrocarbons, carbon monoxide, and the reduction of nitrogen oxides is provided. The unique synergy of the catalyst system, a combination of molecular sieves and noble metals, provides a system that partially or entirely replaces the need for rhodium as a catalyst in three way catalyst systems.

Chemical process and catalyst

Abstract: A catalyst which comprises zinc, together with an effective amount of a platinum group metal on a support which is a material having the silicalite structure, the framework of said material consisting essentially of silicon and oxygen atoms or of silicon, zinc and oxygen atoms. There is also provided a process for the dehydrogenation of a C2 to C10 paraffin to yield an alkene product which process comprises contacting the paraffin under dehydrogenation conditions with a catalyst according to the invention.

Novel silicon-modified catalyst Si/HZSM-5, it's preparation, and a process for synthesizing high purity p-dialkyl benzene from monoalkyl benzene by using said catalyst

Abstract: This invention relates to the preparation of a novel Si/HZSM-5 catalyst through vapor phase deposition of Si on the surface of HZSM-5 catalyst which is obtained by ion exchanging ZSM-5 catalyst. The source of deposition Si comes from tetraalkyl ortho-silicate (or tetra-alkoxy silane), Si(OR)4, wherein R represents the alkyl group that contains 1-4 carbon atoms. The silicon deposit will substantially not clog the pores of the catalyst. The present invention is to make use of the modified catalyst in the alkylation or disproportionation reactions in order to enhance the yield of p-dialkylbenzene as an ingredient in the final product of aryl compounds such as toluene or ethylbenzene.

Supported catalyst for hydrocarbon synthesis

Abstract: A catalyst for converting synthesis gas, a mixture of hydrogen and carbon monoxide, into a mixture of predominately paraffinic hydrocarbons. The catalyst includes catalytically active amounts of cobalt and a loading-insensitive second metal selected from the group consisting of platinum, iridium, rhodium and mixtures thereof, composited on an aluminia support. The finished catalyst exhibits a positive x-ray diffraction pattern. A metal oxide promoter may also be added.

Ammoxidation of paraffins and catalysts therefor

Abstract: Disclosed is the reaction of propane and isobutane with O₂ and NH₃ to make α,β-unsaturated nitriles and olefins, using certain complex metal oxide catalyst compositions and an excess of the paraffin over both the O₂ and the NH₃. Also disclosed are suitable catalyst compositions for such reactions.

Magnesium chloride supported catalysts for olefin polymerization. XIX. Titanium oxidation states, catalyst deactivation, and active site structure

Abstract: A precise method for the determinations of Ti+2, Ti+3 and Ti+4 was developed. The CW-procatalyst before activation contains mostly Ti+4 ions with 6% Ti+3 and 4% Ti+2 ions. Activation with AlEt3 alone at room temperature reduced all the titaniums to lower valence states consisting of 71% Ti+3 and 29% Ti+2. Reduction is incomplete when methyl-p-toluate was present as external Lewis base during activation: at 25°C the distribution of Ti+4 : Ti+3 : Ti+2 is 36% : 25% : 38%; the distribution at 50°C is 37% : 22% : 40%. Aging of the activated catalyst caused little or no changes in the distribution of [Ti+n]; whereas the catalytic activity decays rapidly with aging. The aged catalysts have polymerization activity comparable to the decreased activity of the catalyst during a polymerization. The [Ti+n] was determined for the CW-catalyst during the course of a decene polymerization; they were found to be Ti+4 : Ti+3 : Ti+2 = 30% : 27% : 43%, which did not change with polymerization time. These results suggest that the reducibility of Ti+4 species by AlEt3 or 3AlEt3/MPT to different valence states is predicated by their structures. These species do not undergo further changes in their oxidation states during either aging or polymerization. Their decays probably involve nonreductive metathesis reactions like those known for zirconium alkyls. Possible structures for the stereospecific and nonspecific sites are proposed.

Vanadium Oxides (V2Ox) Catalysts for Dry-Type and Simultaneous Removal of Sulfur Oxides and Nitrogen Oxides with Ammonia at Low Temperature

Abstract: In order to develop highly functional catalysts for a dry-type, simultaneous removal of sulfur oxides (SOx) and nitrogen oxides (NOx) the catalytic activities of V2Ox/TiO2, V2Ox/TiO2/AC(activated carbon) and V2Ox/AC (4

A process for producing ethylene oxide

Abstract: This invention relates to an ethylene oxide process utilizing a catalyst comprising silver supported on an alumina promoted by an alkali metal and rhenium characterized in that at normal operating conditions the concentration of the chlorohydrocarbon moderator in the gas passing over the catalyst is increased during the operation of the catalyst.

Influence of support on the availability of nickel in supported catalysts for hydrogen chemisorption and hydrogenation of benzene

Abstract: Oxides such as SiO2, γ-Al2O3, TiO2(anatase and rutile), ZrO2 and MgO with different properties have been used as supports for loading nickel by the pore volume impregnation method. Catalysts were calcined in air at 723 K for 6 h before reduction at the same temperature. Surface area and acidity measurements, X-ray diffraction and hydrogen and oxygen adsorption measurements along with hydrogenation of benzene were used as tools for characterising the catalyst. A measure of the availability of nickel in the bulk and on the surface of the catalyst is given by the O2/H2 ratio. In a metal–support system there is always a possibility of an interaction. The reducibility of catalysts depends on the availability of nickel ions determined by the support properties and the extent and type of interaction, and follows the order Ni/SiO2 > Ni/TiO2. (R)≈ Ni/ZrO2≈ Ni/TiO2(A) > Ni/γ-Al2O3 Z.Gtc Ni/MgO. The benzene hydrogenation activity was maximum around 433 K and for Ni/TiO2(A) it occurred beyond 473 K. Easily reducible Ni/SiO2 showed the highest activity and difficult-to-reduce Ni/MgO showed no appreciable activity. The turnover number (TON) for benzene hydrogenation is dependent on the available metal area and on the crystallite size. A smooth correlation between TON and the dispersion (Smetal//S,B.E.T.) is observed.

Carrier for gas-treating catalyst, method for production thereof and gas-treating catalyst incorporating said carrier therein

Abstract: A carrier for a waste gas-treating catalyst, comprising an inorganic refractory oxide containing a composite oxide of titanium and zirconium possessing a crystalline structure of ZrTiO 4 , which is produced by heat-treating a substance containing a titanium compound and a zirconium compound at a temperature in the range of 600° to 1,000° C., and a catalyst for treatment of a waste gas comprising the carrier deposited a catalytically active component.

Catalyst for carbon monoxide oxidation

Abstract: A catalyst for the combination of CO and O2 to form CO2 which includes a platinum group metal--e.g., platinum; a reducible metal oxide having multiple valence states--e.g., SnO2 ; and a compound which can bind water to its structure--e.g., silica gel. This catalyst is ideally suited for application to high-powered, pulsed, CO2 lasers operating in a sealed or closed-cycle condition.