Acid silica-alumina

Phenylacetaldehyde can be obtained in high yield by vapor-phase isomerization of styrene oxide, for example, with alkali-treated silica-alumina [147]. Another process starts from phenylethane-l,2-diol, which can be converted into phenylacetaldehyde in high yield. The reaction is performed in the vapor phase in the presence of an acidic silica alumina catalyst [148]. 

Friedel-Crafts catalysts and hydrogen halides, protic acids, silica-alumina-type catalysts, or other protic catalysts are effective. 

Soil, sediment (2,3,7,8-TCDD) Soxhlet extraction of sample volume reduction clean-up on basic silica/acidic, silica/alumina, elution with CH2CI2 in hexane analysis clean-up on silver nitrate silica or 2,3,7,8-TCDD-specific alumina, elution with CH2CI2 in hexane analysis repeating of clean-up or extraction if needed HRGC/LRMS (SIM) HRGC/MS/MS (SIM) 1 ng/g <1 ng/g 40-90 57-102 Simon et al. 1989... 

For silica hinder, Choudhary and his co-workers[1,2] showed in the case of H-gallosilicate that inter-crystalline and intra-crystalline acidity decreased appreciably, resulting in a decrease in total acidity. As in the case of alumina binder, Sousa-Aguiar et al.[7] found a similar interaction of silica binder with ultra-stable Y zeolite, generating an acidic silica-alumina compound. 

Another example presented was for cumene cracking, which is straightforward with acidic (silica-alumina) catalyst ... 

By increasing the hydrogenation activity of the catalyst relative to its acidity, the product distribution from normal paraffin reactants can be dramatically changed. For example, for the hydrocracking of normal decane at comparable conditions, the following iso-to-normal ratios for the combined pentanes and hexanes were obtained with three different metal compositions on a single, acidic silica-alumina support ... 

Persulfate salts, hydrogen peroxide, peracetic acid Amine oxides, acid thickeners, cellulose gums, polyacrylic acid Silica, alumina, calcite Water, salts... 

It has been indicated by several investigators that strong acids rather than weak acids, Lewis acids rather than Bronsted acids favor coke formation, and that the presence of transition metal ions as impurities, e.g., Fe and Ni ions, accelerate the formation of coke. It was reported that coke formation on a nonacidic silica was less than one-twentieth that on acidic silica —alumina. Coke deposition became less serious as the strong acid sites of silica —alumina were weakened by NaOH treatments. Coke formation from hydrocarbons is usually less serious in the case of solid bases. It is reported that the deactivation of MgO and Li/MgO for methane coupling was due to sintering and loss of alkali. ... 

Direct cracking of bio-oils in a fixed-bed reactor has been studied over various catalysts, viz. H-ZSM-5, H-Y, H-mordenite, silicalite, and silica-alumina in the temperature range of 29CM-10°C [238-240]. H-ZSM-5 was the best catalyst yielding 28wt% of hydrocarbons like toluene, xylenes, and trimethylbenzenes [239]. The hydrocarbon yield further decreased in the order H-Y (14wt%) > silica-alumina (13 wt%) > silicalite (5 wt%) > H-mordenite (4 wt%), with significant differences in product distribution ZSM-5 mainly produces aromatics, while the less acidic silica-alumina and the non-acidic silicalite mainly form aliphatics. 

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