Philips catalysts

The Philips catalyst [290] is probably the most important. It is still used for producing over 60% of the world s polyethylene. The most frequently used kind is prepared by impregnating a support (silica, silicoalumina, etc. with a surface area > 200 m2 g-1) with Cr compounds, drying and activating with a stream of dry air (with addition of CO) at 700-1100 K. Chromates are assumed to be formed, but only a small part forms active centres... 

Equation 2.87 can be used to represent the CLD of polyolefins made with the combination of two or more metallocenes very well [35, 38]. This is a reasonably easy case, since the individual metallocenes can be tested separately to obtain the values of Flory s T parameter. For multiple-site catalysts, such as heterogeneous Ziegler-Natta and Philips catalysts, the procedure for obtaining r values for each site type is more elaborate and involves the deconvolution of the MWD into several Flory s distributions. This subject will not be covered in this chapter the reader is directed to references 39 and 40 at the end of the chapter for more information on this subject. Suffice to say that MWD deconvolution involves the use of a non-linear least-squares optimization routine to... 

Method of synthesis Ziegler or Philips catalysts are used in solution or gas phase reactions to obtain LLDPE. Octene copolymer with ethylene is obtained in solution process and butene and hexene are copolymerized with ethylene in gas phase reactors also metallocene catalyst are in use ... 

Phetharbital [357-67-5] pH Glass electrode Philips 2P Process Phillips catalysts... 

J. Philips and M. Teman, eds.. Proceedings of the 9th International Congress on Catalysis, Vol 3, Characterisation and Metal Catalysts, Chemical Institute of Canada, Ottawa, 1988. 

Catalyst Manufacture, Alvin B. Stiles and Theodore A. Koch Handbook of Grignard Reagents, edited by Gary S. Silverman and Philip E. Rakita... 

Contact process for SO3/H2SO4 patented by P. Philips of Bristol, UK (tlie original platinum catalyst was. subsequently replaced by ones ba.sed on V2O5). 

The conventional sol-gel method was employed for the preparation of Ti02 and A1 (5.0- and 10.0-mol-%)-TiO2 catalysts. And these catalysts were characterized by XRD[model PW 1830 from Philips], SEM[model JEOL-JSM35CF], XPS[ESCA 2000], and TPD analyses for the elucidation of siuface phenomena. 

Chemical composition was determined by elemental analysis, by means of a Varian Liberty 200 ICP spectrometer. X-ray powder diffraction (XRD) patterns were collected on a Philips PW 1820 powder diffractometer, using the Ni-filtered C Ka radiation (A, = 1.5406 A). BET surface area and pore size distribution were determined from N2 adsorption isotherms at 77 K (Thermofinnigan Sorptomatic 1990 apparatus, sample out gassing at 573 K for 24 h). Surface acidity was analysed by microcalorimetry at 353 K, using NH3 as probe molecule. Calorimetric runs were performed in a Tian-Calvet heat flow calorimeter (Setaram). Main physico-chemical properties and the total acidity of the catalysts are reported in Table 1. 

Two catalyst systems were developed by Standard Oil and Philips petroleum. Standard Oil process uses metal catalyst such as molybdenum trioxide on supports like alumina or titanium or zirconium dioxide. The process is carried out at 200-300°C at Organisation and Qualities... 

The 11 nm-sized Ti02 were crystallized using either hydrothermal or thermal methods from 100 nm, amorphous gel spheres. The Ti02 crystal and agglomerate sizes were determined by X-ray diffraction (Philip 1080) and transmission electron microscopy (JEOL JEM 2010), respectively. The surface area and chemistry of the nanostructured Ti02 were analyzed by nitrogen physisorption (Coulter SA 3100) and Fourier transform infrared spectroscopy (FTIR, Perkin-Elmer GX 2000). Metal catalyst was deposited by incipient... 

Previous studies in conventional reactor setups at Philip Morris USA have demonstrated the significant effectiveness of nanoparticle iron oxide on the oxidation of carbon monoxide when compared to the conventional, micron-sized iron oxide, " as well as its effect on the combustion and pyrolysis of biomass and biomass model compounds.These effects are derived from a higher reactivity of nanoparticles that are attributed to a higher BET surface area as well as the coordination of unsaturated sites on the surfaces. The chemical and electronic properties of nanoparticle iron oxide could also contribute to its higher reactivity. In this work, we present the possibility of using nanoparticle iron oxide as a catalyst for the decomposition of phenolic compounds. 

Vanadium phosphate catalysts were prepared by heating V2O4, phosphorus acid, either H3PO4 or H4P2O7, and water together in an autoclave at 145°C for 72 hours. Afterwards, the solid produced was recovered, washed with distilled water and dried in air at 120°C for 16 hours. Detailed preparation procedure is described in [79]. Such prepared precursors were activated in n-butane/air at 400°C to form the final catalysts. TEM and EELS are used to study the catalysts in Philips CM200 PEG microscope. 

A series of Chromia-Alumina aerogel catalysts containing different contents of chromium was prepared by autoclave method. The specific areas of the catalysis were measured with Ng at 77°K according to the BET method. Their structural properties were determined from the X ray diffraction patterns recorded on a philips diffractometer PW 1050/70. EPR measurements were performed with a 8ruker ZOO TT spectrometer at 77°K operating in X band. DPPH was used as the g value standard. Kinetic data were obtained in dynamic pyrex microreactor operating at atmospheric pressure as described elsewhere (ref. 3). 

Powder X-ray diffraction (XRD) patterns of the catalysts were obtained using a Philips APD X-ray diffraction spectrometer equipped with a Cu anode and Ni filter operated at 40 kV and 20 mA (CuKa = 0.15418 nm). Iron phases were identified by comparing diffraction patterns of the catalyst samples with those in the standard powder XRD file compiled by the Joint Committee on Powder Diffraction Standards published by the International Center for Diffraction Data. 

Apart form the aforementioned highly enantioselective hetero-Diels-Alder reactions, that proceed with very low catalyst loadings, the catalytically accessible enolates have also been used for related intramolecular Michael reactions (Philips et al. 2007) and for the desym-metrization of 1,3-diketones yielding cyclopentenes via an intramolecular aldol reaction (Wadamoto et al. 2007). The formation of cyclopentenes, however, presents a special case, so—depending on the stereochemical nature of the enone substrates (s-cis or s-trans) and the stereochemistry of the final products—two different mechanisms are discussed in the literature. Whereas /ran.v-cycl open (cries are proposed to be available upon conjugate addition of a homoenolate to chalcones,... 

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