Catalyst continued Kieselguhr

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

Catalytic tests in sc CO2 were run continuously in an oil heated flow reactor (200°C, 20 MPa) with supported precious metal fixed bed catalysts on activated carbon and polysiloxane (DELOXAN ). We also investigated immobilized metal complex fixed bed catalysts supported on DELOXAN . DELOXAN is used because of its unique chemical and physical properties (e. g. high pore volume and specific surface area in combination with a meso- and macro-pore-size distribution, which is especially attractive for catalytic reactions). The effects of reaction conditions (temperature, pressure, H2 flow, CO2 flow, LHSV) and catalyst design on reaction rates and selectivites were determined. Comparative studies were performed either continuously with precious metal fixed bed catalysts in a trickle bed reactor, or discontinuously in stirred tank reactors with powdered nickel on kieselguhr or precious metal on activated carbon catalysts. Reaction products were analyzed off-line with capillary gas chromatography. 

The equilibrium is slow except in the presence of a catalyst. Typically, vanadium catalysts, which consist of V0(S04) supported on kieselguhr, are used to push the equilibrium to the right-hand side. Since the equilibrium shifts in favor of the starting materials with increasing temperature, as low a temperature as possible (ca. 425 °C) is employed, together with continuous removal of the SO3 by absorption into sulfuric... 

Z-Arg(Pmc)-OH.CHA (33.57 g, 49.8 mmol) is converted to the free acid to give a foam, which is then taken up in MeOH (250 mL). Palladium (10%) on charcoal (3.05 g) is added under N2 and hydrogenolysis is continued overnight. Catalyst is removed by filtration through kieselguhr, the solvent... 

Enzymic interesterification is a recent development of considerable promise. Its advantage over the more conventional procedures lies in the additional control of product composition. The lipase, coated on to a support material (kieselguhr, hydroxylapatite, alumina) in the presence of a little water, supports interesterification at about 40 °C and usually requires 16-70 h for complete reaction but can be shorter depending on catalyst activity. The process may be operated in a batch or continuous manner. The substrate is a natural oil or fat to which may be added a second oil or fat and/or a particular fatty acid or fatty acid mixture. Three types of enzyme are available. One type (from Candida cylindricae, Coryne-bacterium acnes or Staphylococcus aureus) is nonspecific and leads to complete randomization of all acids at all positions. The product is the same as that obtained from the ordinary catalytic process. A second type of lipase (from Aspergillus niger, Mucor favanicus, Rhizopus arrhizus, / . delemar... 

Chemical production routes for ethanol synthesis use mainly ethylene hydratiza-tion [route (c) in Topic 5.3.1]. The direct ethylene hydratization option uses solid acid catalysts (e.g., H3PO4 on kieselguhr, montmorillonite, or bentonite) in a continuous gas-phase reaction at 60-80bar pressure and 250-300 °C. At an adjusted ethylene conversion of 5%, the selectivity to ethanol is 97%, with diethyl ether and acetaldehyde being the major side products. 

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