铁锆氧化物催化剂上苯酚和甲醇气相邻位烷基化反应

采用共沉淀法制备了不同锆含量的铁锆氧化物催化剂, 考察了它们在苯酚和甲醇气相邻位烷基化反应中的催化性能. 结果表明, 铁锆两组分氧化物催化剂具有良好的催化活性和邻位选择性, Zr、Fe摩尔比为0.5/100的催化剂上苯酚的转化率达到99.2%, 主要产物邻甲酚和2,6-二甲酚的选择性分别为22.6%和77.0%, 随着反应温度的提高, 2,6-二甲酚的选择性增加. 铁锆氧化物表面存在的相对较强的酸碱中心可能是获得较高苯酚转化率和2,6-二甲酚选择性的主要原因.     

酚类在芳烃溶剂中的缔合溶液热力学

用凝固点降低法测量了对甲酚、间甲酚、邻甲酚、2,4-二甲酚、2,6-二甲酚以及对甲酚+间甲酚、对甲酚+邻甲酚、间甲酚+邻甲酚、2,4-二甲酚+2,6-二甲酚的1:1摩尔比混合物等为溶质, 溶剂为苯或对二甲苯的活度系数, 用Wiehe-Bagley型的连续缔合模型对数据进行了处理, 得到了各种酚的自缔合常效K_A. 在同一溶剂中, K_A依下列顺序减小: 对甲酚>间甲酚>邻甲酚; 2,4-二甲酚>2,6-二甲酚. 各混合酚的表观K_A 介于两种纯酚的K_A之间.     

CuMgAl类水滑石负载VO3-,MoO42-和WO42-催化剂的为波微波合成及其催化苯酚羟化活性

采用微波晶化法合成了三元CuMgAl类水滑石化合物前体,进一步在微波作用下制备了负载VO3-,MO42-和WO42-的类水滑石催化剂.X射线衍射、红外光谱和扫描电镜结果表明,酸根离子很好地负载在类水滑石表面.苯酚羟化反应结果显示,前体中Cu2+/Mg2+摩尔比为3:1时其催化性能最佳,苯酚转化率达到42.8%,邻/对比接近2:1.负载VO3-后催化剂活性升高,苯酚转化率最高达59.2%,而邻对比降为1.2:1.负载MoO42-的类水滑石与前体相比,苯酚转化率下降了约4%,但对苯二酚的选择性有较大提高,邻/对比达到1:6.而负载WO42-后催化剂活性和选择性明显下降.     

CuMgAl类水滑石负载VO3^-,MoO4^2-和WO4^2-催化剂的微波合成及其催化苯酚羟化活性

采用微波晶化法合成了三元CuMgAl类水滑石化合物前体,进一步在微波作用下制备了负载VO3^-,MoO4^2-和WO4^2-的类水滑石催化剂.X射线衍射、红外光谱和扫描电镜结果表明,酸根离子很好地负载在类水滑石表面.苯酚羟化反应结果显示,前体中Cu^2＋/Mg^2＋摩尔比为3：1时其催化性能最佳,苯酚转化率达到42.8%,邻/对比接近2：1.负载VO3-后催化剂活性升高,苯酚转化率最高达59.2%,而邻对比降为1.2：1.负载MoO42-的类水滑石与前体相比,苯酚转化率下降了约4%,但对苯二酚的选择性有较大提高,邻/对比达到1：6.而负载WO42-后催化剂活性和选择性明显下降.     

TiO_2/MCM-41催化苯酚与碳酸二甲酯邻位烷基化研究

采用等体积浸渍法制备了一系列Ti O_2/MCM-41催化剂,并对其进行X射线衍射、N2吸附-脱附、吡啶吸附红外光谱、NH3程序升温脱附和CO_2程序升温脱附等手段对Ti O_2/MCM-41催化剂的结构性质进行了表征。在气相连续流动固定床反应器上,对催化剂催化性能进行了评价,并研究了催化剂结构及酸碱性对苯酚甲基化反应合成邻甲酚的影响。结果表明:MCM-41经Ti O_2改性后,Ti O_2/MCM-41催化剂上Lewis酸中心和弱碱性中心的数量都不断增加,催化剂酸碱中心的存在明显提高苯酚邻位甲基化反应的活性和邻甲酚选择性。过高的酸中心和碱中心数量会引起邻甲酚的进一步邻位甲基化。最佳工艺条件下,苯酚转化率为85.8%,邻甲酚选择性为60.1%。     

HZSM-5沸石分子筛上苯酚与甲醇的烷基化反应

 在n（PhOH）／n（CH3OH）＝1,WGSV＝0．5h－1,T＝673K的反应条件下,研究了HZSM－5,HZSM－23和改性HZSM－5分子筛上苯酚与甲醇烷基化反应的规律．结果表明,分子筛外表面的酸中心对苯酚烷基化反应的贡献较大．用4－甲基喹啉使分子筛外表面的酸中心中毒后,影响反应产物选择性的主要因素是分子筛的孔径．孔径较小的HZSM－23分子筛对提高芳香醚的选择性,抑制二甲酚的生成和提高对甲酚的选择性有利．间甲酚和二甲酚可以在HZSM－5沸石的孔道内生成,但在HZSM－23的孔道内受到抑制．用P2O5,MgO和Sb2O3对HZSM－5改性都可以提高芳香醚的选择性,降低甲酚和二甲酚的选择性．随着氧化物负载量的增加,邻甲酚选择性升高．适度的氧化物改性可以提高对甲酚的选择性,改性效果为Sb2O3＞P2O5＞MgO．     

2，6-二甲酚合成产物的色谱分析

2,6-二甲酚是工程塑料聚苯醚(PPO)的单体,它是由苯酚和甲醇在催化剂存在下高温反应生成。在合成过程中.根据所用催化剂不同而得到不同甲基取代位置的产物。虽然主要产物是由催化剂决定,但是不可避免地还会产生其它的甲酚、二甲酚、三甲酚的异构体及副产物。甲酚类化合物存在多种异构体,组分复杂,化学性质相近。对它们的分离测定一直是分析工作者十分关心和感兴趣的问题。用一般填充柱色谱难以获得满     

二氧化硅负载磷钨酸铵催化苯酚氧化溴代反应

以溶胶-凝胶法制备的二氧化硅负载磷钨酸铵为催化剂,溴化钾为溴源,双氧水为氧化剂,冰醋酸为溶剂,实现了苯酚的催化氧化溴代反应。 探讨了催化剂负载量、催化剂用量和反应时间等反应参数对氧化溴代反应的影响。 结果表明,溶胶-凝胶法制备的负载磷钨酸铵仍具有典型的Keggin结构;在室温的温和条件下,该催化剂表现出较强的催化苯酚氧化溴代反应活性和较高的对溴苯酚选择性,在实验优化条件下,苯酚转化率达到95.4%,对邻比达到3.2;而且催化剂易回收,重复4次使用后,催化活性有所降低,苯酚转化率为87.4%,对邻比为1.6。     

H6PMo9V3O40/SiO2催化剂催化酚类化合物选择性硝化

为创建洁净高效的酚类化合物硝化工艺,以杂多酸H6PMo9V3O40(PMAV3)为活性组分,硅胶为载体,浸渍法制备了负载型催化剂PMAV3/SiO2,采用红外光谱、X射线衍射谱、N2吸附-脱附法及TG-DSC分析等测试技术对该催化剂的结构及热稳定性进行了表征;考察了该催化剂对多种酚类化合物硝化反应的催化性能。结果显示,该催化剂对多种酚类化合物的硝化反应具有很强的催化活性和区域选择性,产率为83.7%~94.5%,其中苯酚、邻甲酚、邻氯苯酚和邻氟苯酚以邻位硝化产物居多,水杨酸的对位硝化产物占绝对优势;负载催化剂的织构性质与载体相近,但随负载量增加,比表面积逐渐降低;PMAV3/SiO2的热稳定性好于本体PMAV3。催化剂回收容易,重复使用5次,活性基本不变。     

负载型钾盐催化剂用于合成苯甲醚的研究

采用固定床连续进料的反应器代替传统间歇反应釜作为评价反应器,以环境友好的碳酸二甲酯为甲基化试剂,由苯酚合成苯甲醚的反应新工艺。采用SiO2负载的钾盐类催化剂,考察了反应温度、进料空速、原料配比、活性组分负载量以及催化剂用量等对反应性能的影响。研究表明,在该负载型钾盐催化剂上苯酚的转化率均较高,且生成苯甲醚的选择性较好。尤其是在KF/SiO2催化剂上,在DMC/苯酚摩尔比为2∶1,进料空速为2 h-1,反应温度为250℃时,苯甲醚收率和选择性分别高达93.93%和98.19%。而且该负载型催化剂活性比较稳定,未发现活性组分流失,反应运行16 h催化剂未见失活。     

ORTHO-selective phenol methylation over iron-magnesium oxide catalysts

Alkylation of phenol to ORTHO-cresol and 2,6-xylenol with methanol in the presence of iron and iron-magnesium oxide catalysts was investigated. The catalysts displayed high activity and stability. Addition of magnesium oxide to the iron catalyst increases its selectivity towards C-alkylation in ortho-position. It was found that the active phase in the investigated catalysts is highly dispersed magnetite or mixed spinel of Fe(MgFe)O₄ type. It is noticed that if Fe⁺² ions are replaced by Mg⁺² ions in the spinel the basicity of the bifunctional catalyst is augmented, increasing ortho-selectivity of alkylation.     

Ortho‐Alkylation of Phenol with Methanol Using Pb‐Cr Promoted Magnesium Oxide Catalysts

In this study, Pb‐Cr promoted magnesium oxide catalysts were used to catalyze the ortho‐alkylation of phenol in the presence of excess methanol. The Cr/MgO catalyst exhibited a high conversion of phenol and a relatively high selectivity for the ortho‐alkylation of phenol. The catalytic activity and the stability of Cr/MgO were improved by the addition of a fairly small amount of Pb. The Pb‐Cr/MgO catalyst showed specificity for the ortho‐alkylation of phenol, which was proved by a series of phenol derivative reactions with methanol.     

Performance of HZSM-5 as Catalyst for Alkylation of Methyl naphthalene with Methanol in Supercritical Phase

The alkylation of methylnaphthalene（MN） with methanol in the presence of HZSM-5 is a promising route for producing 2,6-dimetylnaphthalene（2,6-DMN） with a high selectivity. However, the conversion of MN is very low and the catalyst will be deactivated rapidly with increasing time on stream. In this study, the effects of the reaction pressure on the reactivity, selectivity and life of the catalyst of alkylation of MN over HZSM-5 modified by BaO were investigated. It was observed that with the enhancement of pressure, the conversion of MN increased, but the selectivity of 2,6-DMN kept unchanged, which was about 40% -42%. When the alkylation was carried out under a supercritical condition, the conversion of MN was 3-6 times higher and the life of catalyst was 25-30 times longer than those at an ambient pressure. The thermogravimetric analyses of the deactivated catalysts at different reaction pressures indicate that the amount of coke deposited on the catalysts was about 10% to 12 %, and the coke-burning reactions mainly took place in a temperature range from 720 to 860 K, and the apparent activation energies of the coke-burning catalysts at 0. 1 MPa（ 10 h） and 7. 6 MPa（ 108 h） were, respectively, 65.90 and 84. 72 kJ/mol. It is concluded from tile results that the supercritical condition is advantageous to enhancing the conversion of alkylation and extraction in situ, and to transporting those high molecular-weight poly-aromatic compounds so as to extend the catalyst life successively.     

Mg/Ce-USY分子筛催化苯酚甲醇烷基化

采用Mg、Ce双金属对USY分子筛催化剂进行改性.通过XRD、SEM、N_2吸附-脱附、NH3-TPD、Py-FTIR和TG-DTA分析方法对催化剂进行了表征.结果表明,双金属改性并没有改变USY的孔道结构,活性组分均匀负载在USY分子筛表面;Mg的加入能够更好地促进Ce元素在USY表面的分散,改性金属元素之间的酸碱相互作用显著提高催化剂表面弱酸强度的L酸中心数量.将改性催化剂应用于苯酚甲醇烷基化反应,邻甲酚选择性达到68.7%,高于Ce-USY的42.4%.     

固体酸催化烯烃改性生物油酚类化合物研究

选取生物油中含量较高的愈创木酚、儿茶酚和苯酚为酚类模型化合物,以蒙脱土K-10负载的Cs2.5H0.5PW12O40为固体超强酸催化剂,苯酚/1-辛烯烷基化反应为探针,考察了催化剂负载量,反应温度及物料摩尔比等因素对酚类烷基化反应的影响.结果表明,在60～100℃范围内,30%Cs2.5H0.5PW12O40/K-10对苯酚烷基化反应具有很好的催化活性和选择性,原料摩尔比为1时苯酚氧烷基化产物的选择性最好.愈创木酚中甲氧基的位阻效应使其转化率在相同条件下比苯酚低很多,相应氧烷基化产物的选择性也很低.儿茶酚与1-辛烯反应主要生成单羟基氧烷基化产物,100℃时选择性仍高达96%.升高温度有利于烷基化改性反应的进行,但产物中氧烷基化产物的选择性随着温度升高而降低.     

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.     

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。     

Determination of phenols in soil by supercritical fluid extraction-capillary electrochromatography

A new analytical procedure is developed to couple supercritical fluid extraction with capillary electrochromatography (SFE-CEC) to extract and determine phenols in soil. Ten phenols consisting of phenol, methylphenols (p-cresol and o-cresol), dimethylphenols (3,5-xylenol, 3,4-xylenol and 2,6-xylenol), trimethylphenol, ethylphenols (p-ethylphenol and o-ethylphenol), and o-isopropylphenol are investigated. The use of supercritical CO2 with 10% methanol as the organic modifier was found to give satisfactory extraction of alkylphenols from soil at 1200 p.s.i. and 50 degrees C for 45 min under a total extractant flow-rate of 0.2 ml/min (1 p.s.i.=6894.76 Pa). Baseline resolution was achieved for the 10 selected phenols under optimised CEC conditions at 20 kV in a mobile phase of acetonitrile-4 mM Tris, pH 7.0 (35:65) in a 45 cm (25 cm packed with 3 microm ODS) x 75 microm I.D. fused-silica capillary column. Using SFE with a 10-fold preconcentration factor, all alkyl-substituted phenols in soil can be determined with detection limits ranging from 0.0032 to 0.014 mg/kg and working range from 0.019 to 2.72 mg/kg. The SFE-CEC procedure developed has been applied successfully to determine phenols extracted from real soil sample contaminated with medical disinfectant. It will provide a rapid method for the direct determination of phenol and alkyl-substituted phenol in soils, with capability for confirmation of unknown peaks.     

Synthesis of ethyl acetate by esterification of acetic acid with ethanol over a heteropolyacid on montmorillonite K10

In present work, liquid phase esterification of acetic acid with ethanol over dodecatungestophosphoric acid (DTPA) supported on K10 montmorillonite was systematically studied and optimization of process parameters was carried out. The 20% m/m DTPA/K10 was found to be the optimum catalyst with 90% acetic acid conversion and 100% ethyl acetate selectivity. The study was also explored to see the feasibility of 20% m/m DTPA/K10 as a catalyst for the alkylation of acetic acid with other alcohols like methanol, iso-propanol and n-butanol. The 20% m/m DTPA/K10 has shown increased activity with the increase in carbon number, at the same alcohol reflux. The results are novel.