Influence of the post-treatment of HZSM-5 zeolite on catalytic performance for alkylation of benzene with methanol

The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment (combined alkali treatment and acid leaching)of parent zeolite and its catalytic performance for benzene alkyl-ation with methanol was investigated.The effect of post-treatment on the textural properties was characterized by various techniques(including ICP-AES,XRD,nitrogen sorption isotherms,SEM,NH3-TPD,Py-IR and TG).The results indicated that the post-treatment could modify the structural and acidic properties of HZSM-5 zeolite.In this procedure,not only additional mesopores were created by selective extraction of silicon but also the acidity was tuned.Consequently,the modified HZSM-5 zeolite showed larger external surface area with less acid sites as compared to the parent zeolite.It was found out that the modified zeolite exhibited a higher benzene conversion and xylene selectivity for alkylation of benzene with methanol as well as excellent life span of the catalyst than conventional ones.This can be explained by the facts that the presence of additional mesopores improved the diffusion property in the reactions.Furthermore,the modified zeolite showed an appropriate Br?nsted acidity for effective suppression of the side reaction of methanol to olefins,thus reduced the accumulation of coke on the HZSM-5 zeolite,which was favorable for the catalyst stability.In comparison with the parent HZSM-5 zeolite, the modified zeolite by alkali treatment and acid leaching showed better performance for the benzene alkylation with methanol.     

Synthesis,characteristics of hierarchical EU-1 zeolite for xylene isomerization probe reaction

Introduced a method of synthesizing hierarchical EU-1 zeolite with organosilanes as additive, and studied the influences of following different kinds of organosilanes on the synthesis of hierarchical EU-1 zeolite: γ-glycidoxy propyl trimethoxy silane(GPTMS), N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxyl silane(APAEDMS),and N-(β-aminoethyl)-γ-aminopropyl dimethoxyl(ethyoxyl) silane(TMPED). The hierarchical EU-1 samples were characterized by XRD, SEM, N_2 adsorption, FT-IR and NH_3-TPD to analyze the crystallinity, morphology, surface area, pore size distribution and acidity. The results showed that hierarchical EU-1 zeolites were successfully synthesized; organosilanes have great influence on crystal morphology of EU-1 zeolites; the exterior surface area of hierarchical EU-1 zeolite, which synthesized with organosilanes(APAEDMS) adding into synthesis system, increased by 62.1% and mesopore volume increased by 129.1% compared with conventional EU-1 zeolites, thus can reduce the diffusional restriction markedly in catalytic reaction. The catalytic performance of hierarchical EU-1zeolites were evaluated in m-xylene isomerization on fixed bed reactor. The catalytic data showed that the isomerization activity PX/X of the hierarchical EU-1 zeolites reached around 24.09% in theoretical thermodynamic equilibrium from 23.83%, and the selectivity of C_8 aromatic hydrocarbon increased from 75.16% to 84.87%. The conversion of p-xylene increased from 16.30% to 18.41%.     

五氯酚在低转速短时间内球磨脱氯（英文）

In order to apply grinding method for degradation of pentachlorophenol (PCP) to an industrial scale, the propor-tion of different materials [CaO, SiO2 and CO(NH2)2] and the size of grinding balls were examined. For saving en-ergy and increasing dechlorination efficiency, the rotation speed and grinding time were maintained at relatively low values. At a mass ratio of grinding bal s to materials (40:1), PCP was added into a big steel jar (300 ml) with other materials to grind at 300 r·min?1 for 5 h. The results indicated that when PCP was mixed with CaO and SiO2 in a molar ratio of 1:60:60, the best dechlorination of 58.4%was achieved. CO(NH2)2 could not be used as hydro-gen donor in the dehalogenation by mechanochemical reaction, since it restrained the dechlorination process. The size of grinding balls has significant effect on the reaction. The experiment with 5 mm steel balls indicates that the weight is too light to provide appropriate energy for the reaction, while steel balls of 10 and 15 mm could give better dechlorination reaction. It indicates that dechlorination depends on the mass of balls and fill rate.     

Effect of reaction temperature on Fe–Al analcime formation

The effects of reaction period, temperature, and iron species on the zeolite framework type were studied in this work. Gismondine (GIS) is usually synthesized by hydrothermal method at 80°C from sodium metasilicate and aluminum nitrate as starting materials preferentially independent of the presence/absence of iron source. However, the present work revealed that pure analcime (ANA) could be formed at temperatures more than 120°C. A large polyhedral ANA crystal with a diameter of 180 μm was obtained even at a comparatively low temperature such as 150°C at a short reaction period of 1 week. The presence of iron source promoted the formation of pure ANA. Infrared spectroscopy, X-ray diffraction, and ICP-OES analysis suggested that the iron component added as a reactant was incorporated into the ANA framework through the isomorphous substitution for Al.     

Modeling investigation of geometric size effect on pervaporation dehydration through scaled-up hollow fiber NaA zeolite membranes

A mass transfer model in consideration of multi-layer resistances through NaA zeolite membrane and lumen pressure drop in the permeate sidewas developed to describe pervaporation dehydration through scaled-up hollowfiber supported NaA zeolitemembrane. Itwas found that the transfer resistance in the lumen of the permeate side is strongly related with geometric size of hollow fiber zeolite membrane,which could not be neglected. The effect of geometric size on pervaporation dehydration could bemore significant under higher vacuumpressure in the permeate side. The transfer resistance in the lumen increaseswith the hollowfiber length but decreaseswith lumen diameter. The geometric structure could be optimized in terms of the ratio of lumen diameter to membrane length. A critical value of dI/L (Rc) to achieve high permeation flux was empirically correlated with extraction pressure in the permeate side. Typically, for a hollow fiber supported NaA zeolite membrane with length of 0.40 m, the lumen diameter should be larger than 2.0 mm under the extraction pressure of 1500 Pa.     

Synthesis and characterization of BZSM-5 and its catalytic performance in the methanol to hydrocarbons reaction

Five kinds of BZSM-5 molecular sieve with different Si/B ratio and a SiZSM-5 molecular sieve were prepared by hydrothermal synthesis method followed by acid exchange and pelletization.The samples were characterized by XRD,SEM,FT-IR,ICP,low temperature N_2 physical adsorption and desorption,NH3-TPD and Py-IR.The catalytic performance in the reaction of methanol to hydrocarbons was evaluated in the fixed bed reactor.Compared with SiZSM-5,the amount and strength of Bronsted(B) acid were enhanced by introducing skeleton boron and the activity of the catalyst was greatly improved.The characterization and evaluation results indicated that the BZSM-5 catalyst synthesized from the gel of SiO_2/B_2 O_3 20 with Si/B ratio 74.48 had modest acidity strength,acid amount of 0.18 mmol NH_3·g~(-1) and large mesopore volume of 0.23 cm~3·g~(-1).The B acid ratio was higher and the acid strength of BZSM-5 was weaker than that of AIZSM-5,which could inhibit the deep coke formation and increase the activity stability.B-2 had the best lifetime which could reach 672 h under the same evaluation reaction conditions,due to the best matching of moderate acidity and good diffusion properties.     

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.     

中草药干燥过程中质量退化动力学模型的研究

Curative compositions such as catolpol in Rehmannia Glutinosa, flavone in Ophiopogon Japonicus and ginsenoside Re in Panax Ginseng in Chinese herbs were measured as the experimental indices by the method of high performance liquid chromatography under different drying conditions. The reaction order and parameters of the degradation kinetics model were determined and the model was verified by experiments. It was indicated that by comparing with the thin drying method, the prospective model could predict the degradation of curative compositions with drying time, temperature and moisture content of herbal materials with enough precision and could be used to simulate the degradation in the drying process of Chinese herb.     

Research on the Degradation Kinetics Model in the Drying Process of Chinese Herb

Curative compositions such as catolpol in Rehmannia Glutinosa, flavone in Ophiopogon Japonicus and ginsenoside Re in Panax Ginseng in Chinese herbs were measured as the experimental indices by the method of high performance liquid chromatography under different drying conditions. The reaction order and parameters of the degradation kinetics model were determined and the model was verified by experiments. It was indicated that by comparing with the thin drying method, the prospective model could predict the degradation of curative compositions with drying time, temperature and moisture content of herbal materials with enough precision and could be used to simulate the degradation in the drying process of Chinese herb.     

Synthesis,characterization of triphenyltin grafted on SBA-15 mesoporous silica and its catalytic performance for the synthesis of 4-methylacetophenone

The production of Ph3Sn–O–SBA-15 (Ph3SnSBA) was achieved by heating triphenyltin chloride and SBA-15 in N-methylpyrrolidone at 190 °C for 5 h using triethylamine as a catalyst. The composition, structure, and sur-face physical and chemical properties of Ph3SnSBA were characterized using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), 13C, 119Sn and 29Si solid-state nuclear magnetic resonance (NMR) spectroscopy in situ pyridine infrared spectroscopy (Py-IR), N2 adsorption–desorption isotherms, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of ICP-AES and organic elemental analysis showed that the grafting yield of Sn was 17%(by mass) for Ph3SnSBA. The elemental analysis and solid-state NMR results for Ph3SnSBA were consistent with grafting of triphenyltin on SBA-15. The N2 adsorption–desorption, XRD and TEM analyses showed that Ph3SnSBA retained an ordered hexagonal mesoporous structure, resulting in decreases in the surface area, pore size and mesopore volume, and an increase in acidity as compared with SBA-15. The Hammett acidity function (H0) value and the number of acid sites for Ph3SnSBA, obtained by the Hammett methods, were 2.77–3.30 and 2.07 mmol·g?1, respectively. The Friedel–Crafts acylation of toluene and acetic anhydride over Ph3SnSBA was investigated. The yield of methylacetophenone (MAP) and the selectivity for 4-methylacetophenone (PMAP) were 79.56%and 97.12%, respectively, when the conditions were n (toluene):n (anhydride)=2.0:1.0 with 6%(by mass) catalyst, and heating under reflux for 5 h. The PMAP selectivity stil reached 93.11%when Ph3SnSBA was used for the fifth time under the same reaction conditions.     

HZSM-5 modified by silica CVD for shape-selective production of p-xylene: Influence of in situ and ex situ preparation conditions of the zeolite

HZSM-5 prepared in situ or ex situ from the NH₄-type one was modified by chemical vapor deposition (CVD) of silica for the shape-selective production of p-xylene from methylation of toluene, and the influence of preparation conditions upon the obtained selectivity was studied. The external surface of the ex situ prepared HZSM-5 deteriorated partially, maybe, due to the dealumination caused by moisture contained in the atmosphere. Because of the deteriorated external surface, the CVD could not sufficiently produce a uniform structure of silica to finely control the pore-opening size. On the other hand, the in situ prepared HZSM-5 which was not exposed to the atmosphere kept a fine structure of the external surface on which the silica could be deposited with a regulated structure. Fine control of the pore-opening size was thereby realized more uniformly on the in situ prepared HZSM-5. In situ preparation of H-form zeolite was thus found to be preferential for the CVD modification.     

硅改性HZSM-5沸石上甲苯与甲醇选择性甲基化的研究

采用硅油化学液相沉积法,焙烧后在HZSM-5沸石外表面上形成SiO2涂层,可有效地调控HZSM-5沸石的孔口尺寸。制备了一系列SiO2沉积量不同的Si/HZSM-5催化剂,并进行了甲苯与甲醇选择性甲基化反应。随着SiO2沉积量增加,沸石骨架结构和内表面性质变化不大,而孔口尺寸逐渐缩小,反应中产物对二甲苯的选择性明显提高。     

沸石分子筛孔道和表面化学修饰技术研究进展

沸石分子筛孔道和表面化学修饰是对分子筛进行二次合成的重要手段。本文综述了用离子交换法、化学沉积法和分子反应法等手段对各类沸石分子筛孔道和表面进行化学修饰改性的方法，研究结果表明，孔道和表面化学修饰可以精细调变沸石分子筛的孔道和孔口尺寸，钝化非选择性的表面酸性位，固载活性成分，提高分子筛的反应活性和对目标产物的催化选择性，为设计研制新型功能化的沸石分子筛提供有效的途径。     

Y/composite titania-silica (CTS) supported catalyst for hydrotreating coker gas oil

Y/composite titania-silica (CTS) support was prepared by the in situ growth of CTS on HY zeolite. The effects of HY zeolite pretreatment and Y/CTS modification with P and F for adjusting the acidity of the support were studied. The results showed that the structure of Y/CTS was in the form of CTS as shell and HY zeolite particles as core. The content of HY zeolite affected the acidity, acidity distribution and pore structure of Y/CTS. The density of strong acid sites on the HY zeolite surface could be partly reduced by dealumination with citric acid. This reduced the CTS coverage on the outer surface of the HY zeolite, leading to the increased acidity of Y/CTS. The acidity distribution of the support could also be adjusted by P and F modification. Hydrotreating catalysts were prepared with Y/CTS as support. The catalysts were tested using the hydrotreating reaction of a coker gas oil (CGO). The experimental results showed that the catalyst hydrodenitrogenation (HDN) performance could be remarkably improved by adjusting the acidity of the catalyst support via HY zeolite pretreatment and P and F modification. The catalysts with proper Brönsted (B) acidity and Lewis (L) acidity behaved well in hydrodesulfurization (HDS) and HDN performances.     

调控ZSM-5分子筛酸性的方法研究进展(I)原位合成及后处理

主要对原位合成及后改性方法对ZSM-5分子筛酸性的调控进行归纳总结。原位合成法包括调控硅铝比、控制分子筛表面及体相铝分布,其中可通过改变模板剂类型、合成体系中有无钠离子以及改变硅源、铝源等方式控制铝分布来调控酸性;后处理法包括高温焙烧、水热处理、化学处理等脱铝方式和晶体外延生长、化学硅沉积、外表面毒化等控制外表面酸性来调控分子筛酸性。对分子筛酸性调控方法进行梳理,有利于深入理解不同反应对分子筛酸性的不同要求以及各改性方法对酸性的影响,为合理使用以上方法调控ZSM-5酸性达到最佳的催化性能提供借鉴。     

Beta分子筛改性对催化苯和乙烯烷基化反应的影响

苯和乙烯烷基化反应是重要的乙苯生产途径,Beta分子筛是该过程的重要催化剂。苯和乙烯烷基化反应是一个酸中心催化过程,因此Beta分子筛的表面酸性与催化反应性能之间有密切联系。对工业Beta分子筛进行浸Mg、高温水蒸汽处理和高温焙烧等改性处理,考察改性方法对Beta分子筛酸性及催化苯和乙烯烷基化性能的影响,结果表明,浸Mg改性能增加分子筛总酸量,但酸强度降低,导致催化活性降低,苯和乙烯烷基化反应主要发生在分子筛强酸中心;高温水蒸汽处理后,分子筛酸强度分布基本不变,但总酸量降低,导致乙烯转化率降低;高温焙烧处理导致分子筛结晶度下降,催化活性下降。     

柠檬酸改性原位晶化催化剂的性能及传质扩散行为研究

采用不同浓度的柠檬酸溶液对原位晶化催化剂进行了改性脱铝研究,利用XRD、荧光衍射、氮气吸附、吡啶红外吸附等表征手段对脱铝后的催化剂进行了分析表征,分析表征结果表明柠檬酸能显著调变催化剂孔结构,有效改变中强酸和总酸量。ACE的反应评价结果表明,采用柠檬酸改性后催化剂的裂化能力显著增强,转化率提高3.23%（质量分数）以上、油浆收率降低1.13%（质量分数）以上、液化气质量分数增加2.7%以上、柴油质量分数降低1.94%以上、焦炭选择性变好。说明柠檬酸改性可显著提高原位晶化催化剂酸性位可接近性,从而改善反应选择性,柠檬酸质量分数为0.5%时具有最佳的反应结果。以菲为探针分子测试的催化剂穿透曲线验证了这一点。     

甲苯在硅沉积结合水热改性ZSM-5分子筛上的选择性歧化

采用液相沉积法研究了硅改性剂结合水热改性对择形分子筛的表面酸性和孔结构参数的影响。以甲苯的歧化反应为探针，考察了改性剂的种类和改性次数等因素对催化剂选择性和活性的影响。结果表明，硅改性剂能显著改变分子筛的强酸性，可以对择形分子筛的孔结构进行精细调节。分子筛改性后甲苯的转化率有所降低，但对二甲苯的选择性明显提高。     

改性HZSM-5对甲醇制汽油反应性能的影响

对HZSM-5分子筛改性是提高甲醇制汽油反应催化性能的有效方式,分别用非金属、稀土金属及水热处理对HZSM-5分子筛催化剂进行改性,考察改性方法对HZSM-5分子筛酸性、孔径和比表面积等性质的影响,同时对改性HZSM-5分子筛催化剂催化甲醇制汽油的汽油收率和芳烃含量等指标进行比较。结果表明,经La改性的催化剂可明显提高汽油收率,水热处理的催化剂反应产物汽油中的均四甲苯含量大幅增加。改性催化剂对反应的影响可一定程度验证相关理论。