Selective Ortho alkylation of phenol with alcohols over catalysts derived from hydrotalcite-like anionic clays

The vapour phase alkylation of phenol with a series of alcohols containing different number of carbons ranging from C₁ to C₈ were investigated over catalysts derived from magnesium-aluminium hydrotalcite with Mg/Al atomic ratio 3 (MgAl 3.0-HT). The results indicated that at 623 K the catalytic activity for phenol conversion increased with increasing chain length of linear long chain alcohols to give 2-alkylated linear alkyl phenols, without any isomerisation of the alkyl moiety. Isomorphous substitution of Mg²⁺ by Cu²⁺ or Ni²⁺ in the MgAl 3.0-HT resulted in an increase in selectivity of 2-alkyl and 2,6-dialkylphenols (≈60%) in the alkylation of phenol with 1-hexanol or 1-octanol.     

Alkylation of aromatics. Kinetics of phenol alkylation with methanol

A kinetic study of phenol alkylation with methanol in the presence of -Al₂O₃ has been carried out. A mechanism involving the reaction of phenol and methanol adsorbed on acid-base pair sites is proposed.     

Catalytic alkylation of phenol with methanol over zinc aluminate

Two samples (A and B) of zinc aluminate spinel were prepared and used as catalysts of phenol methylation. Both catalysts were synthesised at hydrothermal conditions from zinc acetate and from various aluminium precursors: aluminium isopropoxide (catalyst A) or basic aluminium nitrate (catalyst B). Catalyst A was pure ZnAl₂O₄ and B - besides ZnAl₂O4 contained traces of -Al₂O₃. Reactions of phenol alkylation with methanol were carried out in the gas phase under atmospheric pressure in a standard flow reactor with fixed bed. Catalysts indicated different properties in dependence on the aluminium precursor used during preparation. In the presence of catalyst A higher selectivity of ortho-methylation of phenol was obtained. Catalyst B was active both in O-alkylation and C-alkylation.     

Side-chain alkylation of toluene with methanol over zeolite catalysts

Catalytic properties of NaX-type zeolites modified by alkali metal cations under hydrothermal conditions have been studied. The highest process efficiency is obtained for CsNaX catalysts. The effect of operation conditions on the process results was examined.     

Liquid-phase alkylation of phenol with long-chain olefins over WOx/ZrO2 solid acid catalysts

The liquid-phase alkylation of phenol with 1-dodecene was carried out over WO_x/ZrO₂ solid acid catalysts. The catalysts were prepared by wet impregnation method using zirconium oxyhydroxide and ammonium metatungstate. Catalysts with different WO₃ loading (5–30 wt.%) were prepared and calcined at 800 °C and catalyst with 15% WO₃ was calcined from 700–850 °C. All the catalysts were characterized by surface area, XRD, and FTIR. The catalyst with 15% WO₃ calcined at 800 °C (15 WZ-800) was found to be the most active in the reaction. The effect of temperature, molar ratio and catalyst weight on dodecene conversion and products selectivity was studied in detail. Under the optimized reaction conditions of 120 °C, phenol/1-dodecene molar ratio 2 and time 2 h, the catalyst 15 WZ-800 gave >99% dodecene conversion with 90% dodecylphenol selectivity. Comparison of the catalytic activity of 15 WZ-800 with sulfated zirconia calcined at 500 °C (SZ-500) and Hβ zeolite showed that activity of SZ-500 was lower than that of 15 WZ-800, while Hβ zeolite showed negligible activity. It is observed that the presence of water in the reaction mixture was detrimental to the catalytic activity of WO_x/ZrO₂. The catalyst 15 WZ-800 also found to be an efficient catalyst for alkylation of phenol with long-chain olefins like 1-octene and 1-decene.     

Alkylation of phenol with methanol on H-beta zeolite

The alkylation of phenol with methanol over Hβ zeolite has been studied. The transformation of primary products of the title reaction was also studied. Anisole was found to be unstable primary product, which was also an important reaction intermediate. On the basis of experimental results, a reaction scheme on Hβ was suggested.     

水滑石类阴离子黏土的合成及催化应用研究进展

水滑石类阴离子黏土具有一些独特的性能,作为催化材料应用广泛。本文就水滑石类阴离子黏土的合成现状进行了概述,对其各种不同的合成方法进行了比较。给出了它作为碱催化剂、氧化还原催化剂以及催化剂载体的应用实例,共引用文献60篇。     

Production of thymol from alkylation of m-cresol with isopropanol over ZSM-5 catalysts: Artificial Neural Network (ANN) modelling

Thymol is one of the most widely used chemicals in the cosmetic and health industries and a known antioxidant. There are different methods for the preparation of thymol. One of the efficient methods for the synthesis of thymol is the alkylation of m-cresol using isopropanol as the alkylating agent and ZSM-5 acid catalysts. Different parameters such as SiO₂/Al₂O₃ ratio, temperature and Weight Hourly Space Velocity (WHSV) can affect the conversion and selectivity of m-cresol alkylation. The application of tools to predict the effect of each of the effective factors and, thus, the proposition of a strong model of reaction conditions will lead to maximum conversion and selectivity. A connectionist tool has been used to evaluate the conversion and selectivity in thymol synthesis. The model simultaneously correlates the thymol selectivity and m-cresol conversion to independent variables. An appropriate statistical analysis has been carried out in order to guarantee the generalization and strength of the deterministic model. The developed network leads to coefficient of determination (R²) of 0.9890 and 0.9889 for the thymol selectivity and m-cresol conversion, respectively. Furthermore, the error analysis shows mean squared error (MSE) values of 2.2060 and 1.8126 for the thymol selectivity and m-cresol conversion, respectively.     

Steam reforming of toluene as model of tar compound over Mo catalysts derived from hydrotalcites

This study evaluated the catalytic activity of Mo catalysts derived from hydrotalcite-like compounds for steam reforming of toluene as a model compound for tar. The catalysts with 1.5, 3 and 4.5 Mo loadings (wt%), denoted as Mo_1.5MgAl, Mo₃MgAl and Mo_4.5MgAl respectively, were prepared by coprecipitation and characterized by BET, XRD, SEM, TEM, FT-IR and UV–VIS. The results showed that toluene conversion increased with increasing molybdenum content. The hydrogen amount depended on two factors: the presence of molybdate species on the surface and the presence of aluminum cations in tetrahedral sites (Mo₃MgAl), with molybdenum influence being more pronounced. The H₂/CO ratio decreased at increasing temperature while, the H₂/CO₂ ratio increased proportionally with temperature. Mo_1.5MgAl catalyst was more selective for CO₂ and H₂, while, Mo₃MgAl and Mo_4.5MgAl were more selective for CO and H₂.     

Heterogeneous acylation of phenol with acetic anhydride over hydrotalcite-like compounds

Liquid phase acylation of phenol with acetic anhydride was studied over the mixed oxides obtained from Mg-Al, Ni-Al, and Cu-Al hydrotalcites (HTs). The mixed oxides were characterized by XRD and SEM. The main acylation products of phenol over these oxide catalysts are phenylacetate and o-hydroxyacetophenone.     

Kinetics of methanol steam reforming over COPZr-2 catalyst

The COPZr-2 catalyst, which was prepared in our prophase research, showed good catalytic performance in methanol steam reforming reaction. In this article, the best one was chosen as an example to study the reaction kinetics of methanol steam reforming over this type of catalyst. First, the effects of methanol conversion to outlet CO2 and methanol conversion to outlet CO on methanol pseudo contact time W/FMeOH were investigated. Then by applying the reaction route that methanol direct reforming （DR） and methanol decomposition （DE） were carried out in parallel, the reaction kinetic model with power function type was established. And the parameters for the model were estimated using a non-linear regression program which computed weighted least squares of the defined objects function. Finally, the kinetic model passed the correlation test and the F-test.     

Ce的浸渍顺序对Cu/Zn-Al水滑石衍生催化剂用于甲醇水蒸气重整制氢性能的影响

采用原位合成法在γ-Al_2O_3载体上合成了锌铝水滑石,再经浸渍法制备了Cu/Zn-Al、Ce/Cu/Zn-Al、Cu/Ce/Zn-Al和Cu-Ce/Zn-Al催化材料,使用XRD、XRF、SEM、氮吸附,XPS、H_2-TPR和N_2O滴定等手段对其进行了表征,探讨了Ce的浸渍顺序对Cu/Zn-Al水滑石衍生材料甲醇水蒸气重整制氢反应催化性能的影响。结果表明,Ce的浸渍顺序主要影响催化剂的还原性质,进而影响了其催化性能。其中,Ce/Cu/Zn-Al催化剂的催化性能最佳,在250℃、水醇物质的量比为1.2、甲醇气体空速为800 h~(-1)的条件下,甲醇转化率达到100%;与Cu/Zn-Al催化剂相比,甲醇转化率提高了近40%。     

Kinetics and reaction mechanism of phenol hydroxylation catalyzed by La-Cu_4FeAlCO_3

Phenol hydroxylation is an industrially important reaction, whose main products are catechol and hy-droquinone being diverse applications which are im-portant intermediates for perfumes, drugs, and phar-maceuticals and so on[1]. The processes using H2O2 a…     

稀土掺杂改性对Cu/ZnAl水滑石衍生催化剂甲醇水蒸气重整制氢性能的影响

采用原位合成法在γ-Al₂O₃表面合成了锌铝水滑石,再通过顺次浸渍法制备了一系列掺杂稀土改性的M（M=Y、La、Ce、Sm、Gd）/Cu/ZnAl催化材料,并将其应用于甲醇水蒸气重整制氢反应。探讨了稀土掺杂改性对Cu/ZnAl催化剂催化性能的影响,并采用XRD、SEM-EDS、BET、H₂-TPR、XPS和N₂O滴定等手段对催化剂进行了表征。结果表明,催化剂的活性与Cu比表面积和催化剂的还原性质密切相关,Cu比表面积越大,还原温度越低,催化活性越高。稀土Ce、Sm、Gd的引入能改善活性组分Cu的分散度、Cu比表面积以及催化剂的还原性质,进而提高催化剂的催化活性。其中,Ce/Cu/ZnAl催化剂表现出最佳的催化活性,在反应温度为250 ℃时,甲醇转化率达到100%,CO含量为0.39%,相比Cu/ZnAl催化剂,甲醇转化率提高了近40%。     

Kinetics of esterification of acetic acid with n-butanol over different homogeneous acid catalysts

The esterification reaction of n-butanol and acetic acid has been performed in batch reactor in the presence of different homogeneous acid catalyst, namely sulfuric acid, nitric acid, and para toluene sulfonic acid (p-TSA). The objective of present research work is to investigate kinetic behavior of esterification reaction over the temperature range of 60°C–80°C. The effect of reaction parameter such as catalyst loading varied from 1% to 5% v/v and acid to alcohol molar ratio of 1:1, 1:3, and 1:5 has been observed. A pseudo homogeneous kinetic model has been applied. Kinetic parameters such as equilibrium constant, reaction rate constant, enthalpy, activation energy, and entropy were calculated by the experimental data for different acid catalyst system. It was observed that sulfuric acid gives higher conversion 73% than p-TSA 68.5% and nitric acid 66.25% at temperature of 80°C, 1:1 molar ratio and 3% catalyst concentration. The activation energy was estimated 36448.49, 23324.31 and 19060.156 J/mol K for three different catalyst sulfuric acid, nitric acid and p-TSA respectively. The enthalpy and entropy of the esterification reaction of acetic acid with n-butanol over three different catalysts has been calculated (Enthalpy: 25.788 KJ/mol, 12.256 KJ/mol, 28.320 KJ/mol, Entropy: 88.1 J/mol K, 45.298 J/mol K, 91.44 J/mol K) and found enthalpy is having positive value that shows reaction is endothermic.     

氧化铝负载催化剂作用下以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚(英文)

苯甲醚作为重要的化学品和医药中间体而广泛应用于香料、调味剂及有机合成.液相法是传统的苯甲醚制备工艺,例如在碱性环境下,通过酚钠与硫酸二甲酯反应,溴苯与甲醇反应,酚钠与氯代甲烷反应均可制得苯甲醚.然而,这些方法具有环境处理负担较重和所用原料毒性较强等不足而备受限制.因此,环境友好的绿色苯甲醚合成工艺的开发成为必然,苯酚的气相烷基化工艺由此提出.其中,以碳酸二甲酯(DMC)为烷基化试剂的苯酚气相转化苯甲醚制备方法最受关注.DMC是常用的绿色高效烷基化试剂,但其价格相对较高,在一定程度上增加了苯甲醚制备工艺的复杂性和产品成本.鉴于DMC可由甲醇经氧化羰基化制得,因此以甲醇为烷基化试剂的苯酚气相烷基化转化制备苯甲醚方法成为另一研究热点.然而,与DMC的烷基化性能相比,以甲醇为烷基化试剂的反应产物分布较为复杂,作为苯酚O-烷基化(在苯酚的羟基氧原子上发生的烷基化)产物的苯甲醚相对较难获得,而苯酚的C-烷基化(在苯酚的芳环上发生的烷基化)产物甲基酚产率更易提高.总体而言,与DMC烷基化方法相比,以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚方法有待改善,相关反应机理也更欠明晰,因此具有重要的研究价值.本文研究了γ-Al_2O_3(AA)负载型催化剂上以甲醇为烷基化试剂的苯酚气相转化制备苯甲醚方法,考察了反应温度、气体空速、苯酚与甲醇配比以及催化剂中K负载量和焙烧温度等对反应性能的影响,并分析了该体系中的反应机理.研究表明,在AA上负载的8种化合物(NaCl,MgCl_2,Fe_2(SO_4)_3,Co(NO_3)_2,ZnCl_2,La(NO_3)_3,Ce(NO_3)_3和KH_2PO_4)的催化剂中,KH_2PO_4/AA的催化性能最佳,相应催化剂中K离子负载量为7.53 wt%,于700 oC焙烧8 h.苯酚与甲醇气相反应过程中,苯甲醚最大收率出现在400–450 oC,且随甲醇与苯酚的摩尔比升高而增加,但随空速的提高而降低.另外,在KH_2PO_4/AA催化剂的高K含量,以及低温、高空速、低甲醇含量的物料配比的条件下,对苯酚的O-烷基化过程有利.产物除主产物苯甲醚以外,还有少量甲基苯酚、甲基苯甲醚以及二甲基苯酚等副产物.在K含量为7.53 wt%的KH_2PO_4/AA催化剂作用下,苯甲醚收率最高时反应条件为400–450 oC,空速小于0.18 h儃1,甲醇与苯酚摩尔配比为5.本文所开发的催化剂制备方法简单,反应条件温和,产物收率较高,因此具有较好的应用前景.X射线衍射结果显示,经高温焙烧及固相反应后,KH_2PO_4/AA催化剂中产生了K_3Al_2(PO_4)_3新物相.推测该反应机理是酸性氧化铝促进甲醇脱羟基负离子以及K离子促进酚羟基脱氢质子,所形成的甲基正离子进一步与苯氧基负离子结合得到苯甲醚的"钾离子-酸"双功能催化作用过程     

Compounds responsible for the deactivation of H-USY zeolite during the alkylation of phenol with methanol

H-USY deactivates very rapidly during the alkylation of phenol with methanol at 200°C. The retention in the pores of compounds resulting from successive O- and C-alkylation of phenol (such as polymethylphenols and polymethylanisoles) is responsible for this deactivation. The retention of these compounds in the pores is not due to their steric blockage but to their low volatility and their strong adsorption.

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H-USY 200°C. , - - , ( -). , .

     

Mg-La-HY-SBA-15分子筛催化甲醇烷基化反应

用两步浸渍法制备了Mg-La-HY-SBA-15复合分子筛,在小型固定床反应器上考察了苯酚甲醇烷基化性能;通过SEM-EDS、Py-FTIR等表征手段分析了Mg-La-HY-SBA-15分子筛的孔结构和酸性。结果表明,Mg负载到HY-SBA-15分子筛上且未改变其微介孔结构; Mg改性后降低了载体的总酸量,增加了总Lewis酸,提高了邻甲酚的选择性和收率。     

CuZnAl类水滑石衍生复合氧化物催化环己醇脱氢反应的研究

采用共沉淀法合成了不同CuZnAl配比的类水滑石,通过不同温度焙烧制备其衍生复合氧化物.采用X-射线衍射(XRD)、差热热重(TG-DTA)、N2吸附-脱附和CO2程序升温脱附法(CO2-TPD)对类水滑石和衍生复合氧化物进行了表征.将所得复合氧化物用于环己醇脱氢制备环己酮的反应中考察其催化活性.实验结果表明:CuZnAl类水滑石衍生复合氧化物对该反应具有很高的催化活性,在反应温度220℃时以CuZnAl[n(Cu)/n(Zn)/n(Al)=1.34/0.66/1.0]类水滑石为前躯体,400℃焙烧所得的衍生复合氧化物表现出最佳的催化活性,环己醇转化率高达94.9%,环己酮的选择性近100%.     

Vapor phase alkylation of aniline using ethanol over alkali and alkaline-earth exchanged zeolites-Y

Ethylation of aniline has been investigated over various alkali and alkaline earth metal exchanged zeolites-Y. The basic zeolites-Y were found to have higher activity than acidic zeolites-Y for N-alkylation.