Vapor-Phase Alkylation of Phenol with Tert-butyl Alcohol Catalyzed by H3PO4/MCM-41 (original) (raw)
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Phenol alkylation with isobutene — influence of heterogeneous Lewis and/or Brønsted acid sites
Journal of Catalysis, 2009
Acidic solid catalysts with different types of acidity were used to study the liquid-phase alkylation of phenol with isobutene. A phosphonium ionic liquid immobilized on silica type carrier exhibiting pure Lewis acidity, Amberlyst 15 with pure Brønsted acidity as well as WO 3 /ZrO 2 with both types of acid sites were used for this study. The active sites are postulated based on pyridine-FT-IR and NH 3 -TPD studies, BET analyses, MAS NMR and XRD measurements. The different properties of the chosen catalysts are mirrored in the product distribution of the reaction mixture. It was found that WO 3 /ZrO 2 is a very active and selective catalyst for the production of 2,4-di-tert-butylphenol under mild reaction conditions.
ChemCatChem, 2020
Pyrolysis and liquefaction biocrudes obtained from lignocellulose are rich in phenolic compounds that can be converted to renewable aromatics. In this study, Pt catalysts on reducible metal oxide supports (Nb 2 O 5 , TiO 2), along with irreducible ZrO 2 as a reference, were investigated in the liquid-phase hydrodeoxygenation (HDO) of 4-propylphenol (350°C, 20 bar H 2 , organic solvent). The most active catalyst was Pt/Nb 2 O 5 , which led to the molar propylbenzene selectivity of 77 %, and a yield of 75 % (98 % conversion). Reducible metal oxide supports provided an increased activity and selectivity to the aromatic product compared to ZrO 2 , and the obtained results are among the best reported in liquid-phase. The reusability of the spent catalysts was also studied. The spent Pt/Nb 2 O 5 catalyst provided the lowest conversion, while the product distribution of the spent Pt/ZrO 2 catalyst changed towards oxygenates. The results highlight the potential of pyrolysis or liquefaction biocrudes as a source of aromatic chemicals.
Characterization of Co,Al-MCM-41 and its activity in the t-butylation of phenol using isobutanol
Applied Catalysis A: General, 2004
Co,Al-MCM-41 catalysts with various n Si /(n Co +n Al) ratios were synthesized and extensively characterized by low-angle XRD, TGA/DTG, BET, AAS, DRIFT, UV-Vis DRS and ESR. UV-Vis DRS and ESR studies reveal that cobalt in Co,Al-MCM-41 is highly symmetrical and occurs in tetrahedral coordination. Some of the cobalt atoms are transformed into the cobalt oxide form when n Si /(n Co + n Al) is increased to 20. t-Butylation of phenol with isobutanol was studied in the vapor phase as a model reaction at temperatures between 200 and 500 • C. The products obtained were O-tert-butyl phenol (OTBP), 2-tert-butyl phenol (2TBP) and 4-tert butyl phenol (4TBP). O-Butenyl phenol (OBP) and 2-butenyl phenol (2BP) were also observed along with normal alkylated products. The phenol conversion drastically increased with temperature over all the catalysts. The activity of the catalysts followed the order of Co,Al-MCM-41 (20) > Co,Al-MCM-41 (50) > Co,Al-MCM-41 (80) > Al-MCM-41 (23). The influences of various parameters such as temperature, reactant feed ratio and feed rate, time on stream on conversion and products selectivity were studied and the salient results are discussed.
Vapour phase O-alkylation of phenol over alkali promoted rare earth metal phosphates
Journal of Molecular Catalysis A: Chemical, 2002
The vapour phase synthesis of anisole by O-alkylation of phenol with methanol was investigated over lanthanum, cerium, samarium, and antimony phosphate catalysts promoted with cesium hydroxide. Among various catalysts investigated, the cesium promoted samarium phosphate provided better activity and selectivity. The effect of temperature, contact time, time-on-stream, reusability, and up-scaling of the catalyst were also studied. These studies clearly reveal that the Cs-Sm combination is the superior catalyst for selective O-alkylation of phenol with methanol. The unpromoted catalysts provided more C-alkylated side products. Incorporation of cesium suppressed the formation of side products. The X-ray diffraction analysis of various samples revealed that there is no change in the crystalline composition of the catalysts up on addition of cesium promoter. However, the surface acidity of the catalyst was observed to decrease after the incorporation of cesium promoter as revealed by the temperature programmed desorption study of anhydrous ammonia.
Alkylation of phenol with tert-butyl alcohol catalysed by zeolite Hβ
Applied Catalysis A: General, 1998
Mesoporous silica materials (MCM-41) with different pore sizes were synthesized by using 1,3,5-trimethylbenzene as a micelle expander and used as support material for preparation of containing sulfonic acid ionic liquid catalysts. The-SO 3 H functionalized Brønsted acid ionic liquids ([Ps-mim]HSO 4) were loaded on MCM-41 with different pore sizes by impregnation method and the three composites [1-IL@MCM-41 (2.4, 3.6 and 4.8 nm)] were obtained. Their physicochemical properties were characterized by FT-IR, TG-DSC, N 2 adsorption technique, XRD and TEM. Also, the catalytic performances of 1-IL@ MCM-41 (2.4, 3.6 and 4.8 nm) were evaluated by the alkylation of phenol with tert-butyl alcohol. The effects of reaction temperature, pore size of MCM-41and the recyclability of catalysts on the conversion of phenol and selectivity to products were investigated.
Tertiary Butylation of Phenol Over Solid Acid Catalysts: An Overview on Recent Progress
Advanced Porous Materials
The development of efficient solid acid catalysts for Friedel-Craft alkylation of phenols is of paramount importance in the context of efficiency, safer and cleaner chemical technologies. Therefore, in the present study, we review the current status on the alkylation of phenols, viz., phenol, hydroquinone and cresols, with various alkylating agents such as tertiary butyl alcohol, isobutyl alcohol, isobutylene, methyl tertiary butyl ether, and mono tertiary butyl ether of mono ethyl glycol, over various heterogeneous solid acid catalysts including ordered microporous and mesoporous materials. The focus is devoted on exploring the mechanistic aspects of the titled reactions, the role of the catalysts and their active sites on the product selectivity.
Selective synthesis of p-ethylphenol by gas-phase alkylation of phenol with ethanol
Applied Catalysis A: General, 2014
ABSTRACT The selective synthesis of p-ethylphenol from gas-phase alkylation of phenol with ethanol was studied on zeolites HZSM5 and HMCM22 at 523 K. Phenol reacted directly with ethanol to form ethylphenylether by O-alkylation, and p-and o-ethylphenol isomers by C-alkylation; secondary products were m-ethylphenol and dialkylated compounds. Both zeolites presented similar activity and formed low amounts of ethylphenylether and dialkylated products, but exhibited different ethylphenol isomers distribution. In fact, for a contact time of 99.3 g h/mol the selectivity to p-ethylphenol was 51.4% on HMCM22 and only 14.2% on HZSM5. The superior performance of zeolite HMCM22 for selectively producing p-ethylphenol was due to its narrower pore channels that suppressed the formation of dialkylated products and hampered by diffusional constraints the formation of o-ethylphenol. The maximum p-ethylphenol yield obtained on HMCM22 was 41% at a contact time of 250 g h/mol; for higher contact times, p-ethylphenol was increasingly converted to m-ethylphenol. All the samples deactivated on stream because of coke formation. The carbon amount built on HMCM22 diminished when contact time was increased thereby indicating that coke was mainly formed from the reactants. Additional catalytic runs showed that phenol was the main responsible of catalyst deactivation, probably because of its strong adsorption on surface active sites.