A novel catalyst for alkylation of benzene

In this research, acid-activated and pillared montmorillonite were prepared as catalysts for alkylation of benzene with 1-decene for production of linear alkyl bebzene (LAB). The catalysts were characterized by X-ray diffraction (XRD), FT-IR spectroscopy, scanning electron microscopy (SEM), N₂ adsorption-desorption isotherms, temperature programmed desorption (TPD) of NH₃ and elemental and thermal analysis techniques. The reaction conditions were optimized by varying catalyst concentration, reactants ratio and temperature in a batch-slurry reactor. It was found that acid-activation increased the porosity and surface acidity of the catalysts. Pillaring of the sample improved the surface area, micro-mesoporosity and acidity. Under optimized conditions more than 98% conversion of 1-decene was observed. All products were LABs and no major side reaction was observed.     

Zirconia-supported phosphotungstic acid as catalyst for alkylation of phenol with benzyl alcohol

The liquid-phase alkylation of phenol with benzyl alcohol was carried out using zirconia-supported phosphotungstic acid (PTA) as catalyst. The catalysts with different PTA loadings (5–20 wt.% calcined at 750 °C) and calcination temperature (15 wt.% calcined from 650 to 850 °C) were prepared and characterized by ³¹P MAS NMR and FT-IR pyridine adsorption spectroscopy. The catalyst with optimum PTA loading (15%) and calcination temperature (750 °C) was prepared in different solvents. ³¹P MAS NMR spectra of the catalysts showed two types of phosphorous species, one is the Keggin unit and the other is the decomposition product of PTA and the relative amount of each depends on PTA loading, calcination temperature and the solvent used for the catalyst preparation. The catalysts with 15% PTA on zirconia calcined at 750 °C showed the highest Brönsted acidity. At 130 °C and phenol/benzyl alcohol molar ratio of 2 (time, 1 h), the most active catalyst, 15% PTA calcined at 750 °C gave 98% benzyl alcohol conversion with 83% benzyl phenol selectivity.     

Silica-alumina supported transition metal oxide catalyst for alkylation of aromatic compounds

Titanium oxide on silica-alumina support is described to be an efficient regenerable catalyst for alkylation of aromatic compounds with alkyl halides, alcohols and olefins, and the reaction is proposed to be initiated by the protonated metal active species present in the catalyst.     

Metal ions exchanged montmorillonite as catalyst for alkylation of benzene with 1-dodecene

Summary About 8.5% of benzene was alkylated with 1-dodecene in the presence of Na⁺-montmorillonite. When the reaction was carried out with montmorillonite exchanged with Mn²⁺, Cu²⁺, Ni²⁺, Zn²⁺ and Fe²⁺ ions as catalyst (M²⁺/mont.), 91 to 95% of 1-dodecene was remarkably converted to a mixture of linear monoalkylbenzenes.     

不同条件下苯与丙烯烷基化反应的催化剂失活研究

对不同条件下苯与丙烯烷基化反应Hβ催化剂的寿命、失活催化剂的积炭量和积炭性质进行了研究。在5.7MPa下,随反应温度变化,反应介质在反应过程中所经历的相态变化不同,导致催化剂的寿命、失活催化剂的积炭量和积炭的性质也存在着较大差异。300℃时,反应介质处于接近于体系临界点的超临界相或高压液相状态,催化剂寿命最长,积炭量大。失活催化剂积炭的元素分析及TPO-MS表征结果发现,积炭的碳氢比与反应温度有关,温度越高,碳氢比越高;而积炭的脱炭温度与反应时间（催化剂寿命）相关,催化剂寿命越长,相应的脱炭温度也越高。     

高性能甲苯烷基化合成二甲苯催化剂研究

通过对比不同孔结构分子筛的甲苯甲醇烷基化催化性能,发现分子筛孔道尺寸与目标芳烃分子动力学尺寸的有效匹配以及孔道空间限制效应对反应路径的约束管理,对实现高性能烷基化至关重要。并结合XRD、BET、NH₃-TPD和SEM表征分析,通过先后负载La₂O₃和P₂O₅对硅铝比为60的ZSM-5进行复合改性修饰,提升其骨架水热稳定性的同时,选择性地消除内外表面大部分强酸中心,保留弱+中强酸作为烷基化催化活性位,所得MAT-HZSM-5催化该反应表现出很高的甲醇烷基化效率和良好的反应稳定性,在氮气反应气氛下,连续运行500 h无明显失活迹象,甲苯转化率维持在35%-38%,二甲苯选择性60%-77%,甲醇烷基化效率大于90%。     

New quaternary phosphonium salt as multi-site phase-transfer catalyst for various alkylation reactions

The present work describes the C-alkylation reactions of fluorene and curcumin catalyzed by a new phosphonium salt, benzene-1,3,5-triyltris(methylene))tris(triphenylphosphonium)bromide, as a multi-site phase-transfer catalyst (MPTC). The catalytic efficiencies were found to be quite effective for di- and tetra-alkylation reactions with very excellent yields under mild base and low concentrations of the catalyst. The synthesized MPTC 3 have privileged catalytic activity compared to commercially available single-site phase-transfer catalysts.

     

A BINOL-terpyridine-based multi-task catalyst for a sequential oxidation and asymmetric alkylation of alcohols

Treatment of a BINOL-terpyridine compound with RuCl₃ generates a Ru(II) complex (R)-6. This complex is found to be a novel multi-task catalyst capable of conducting a sequential oxidation and asymmetric alkyl addition to convert primary alcohols to chiral secondary alcohols. The terpyridine-Ru(II) site of (R)-6 catalyzes an efficient oxidation of primary alcohols to aldehydes which then undergo an enantioselective alkylation to generate chiral secondary alcohols when the BINOL site of (R)-6 is combined with ZnEt₂ and Ti(OⁱPr)₄.     

Highly active and stable immobilized aluminium chloride catalyst for alkylation of benzene with 1-dodecene

Summary An AlCl₃ catalyst immobilized on<span lang=EN-US style='font-family:Symbol;mso-bidi-font-family: Symbol;mso-ansi-language:EN-US'>g-Al₂O₃with meso- and macro-pore bimodal structure was prepared and studied in the alkylation of benzene with 1-dodecene in a suspension bed reactor. The catalyst exhibited high activity, selectivity and stability during 1000 h running, with a 1-dodecene conversion of more than 95%, monoalkylbenzene selectivity of 92%, and 2-phenyldodecane (2-Ph) selectivity of nearly 42%.</o:p>     

Overcoming the limitations of anthracene alkylation using SZ-DeAl-DFNS acid catalyst

In situ formation of composite micro-mesoporous dendritic fibrous nano-silica (DFNS) and Al-DFNS was prepared using a cetylpyridinium bromide (CPB) template synthetic system. Dealumination is induced by impregnation of zirconium with flux followed by a sulfuric acid treatment. This procedure results in a series of highly uniform nano-spheres, which exhibit stronger acid property than that of Al-MCM-41. In the selective alkylation of anthracene with tert‑amyl alcohol, SO₄²⁻ modified Zr-contained dealuminated Al-DFNS (SZ-DeAl-DFNS) shows great catalytic activity and higher conversion (60.8%). The DFNS samples were characterized with XRD, SEM, TEM, NH₃-TPD and other techniques. The results reveal that DFNSs consist of center-radial micro-mesopores and that the acid contribution of SZ-DeAl-DFNS is much broader, as compared with amorphous aluminosilicate     

Side-chain alkylation of toluene with methanol over Cs2O-activated carbon catalyst

The side-chain alkylation of toluene to form ethylbenzene or styrene has been investigated using a conventional flow reactor at temperatures near 475°C. Cs₂O (10–20 wt. %)-activated carbon catalyst prepared by an impregnation method showed an excellent activity and selectivity. The calcination temperature of the catalyst and the addition of CO₂ or H₂O into the reactant mixture affected the catalyst activity in a striking manner.

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, , , 475°C. , Cs₂O (10–20 . %) , . CO₂ H₂O .

     

In-water dehydrative alkylation of ammonia and amines with alcohols by a polymeric bimetallic catalyst

An in-water dehydrative alkylation with a novel heterobimetallic polymeric catalyst is described. Thus, a boron-iridium heterobimetallic polymeric catalyst was prepared by ionic convolution of a poly(catechol borate) and an iridium complex. The alkylation of ammonia and amines with alcohols, alkylating agents, was performed with 1 mol % Ir of the heterogeneous catalyst in water without the use of organic solvents under aerobic conditions to give the corresponding alkylated amines.     

Ortho alkylation of aromatic ketimine with functionalized alkene by Rh(I) catalyst

[reaction: see text] The reaction of the imine of aromatic ketones with functionalized alkenes was performed under a catalytic amount of (PPh3)3RhCl, and corresponding ortho-alkylated ketones were obtained after hydrolysis. A variety of functional groups in the alkene were tolerated in this ortho alkylation. This procedure expands the scope of ortho alkylation to the direct ortho functionalization of aromatic ketones.     

Kinetic model for anisol synthesis by methanol alkylation of phenol on a zeolite catalyst

A kinetic model for the reaction of phenol alkylation by methanol on a zeolite catalyst tested is suggested. Estimate of the kinetic parameters confirms the proposed reaction mechanism.

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烷基化催化剂表面酸性及催化性能的动力学研究

在确定关联升温速率、脱附峰温和脱附峰覆盖率的程序升温脱附动力学模型的基础上，通过TPD实验和模型参数估值，建立了表征催化剂酸密度、酸强度及强度分布情况的方法。研究表明，随着活化温度的提高，固体酸催化剂表面酸中心强度分布先变宽后趋于均匀，350?℃活化催化剂的强度分布最宽；催化剂表面酸强度和酸密度随活化温度提高均呈先增大后降低、分别在350 ℃和250 ℃活化温度达到极大值的变化规律。催化剂酸性与催化性能关联的结果表明，随着活化温度的提高，烷基化反应速率常数与总脱附量的变化趋势相同，而催化剂失活速率常数与脱附活化能变化趋势相同；催化剂活性稳定性随其酸强度的增大而变差，催化剂活性与催化剂酸量和酸强度有关。