Synthesis of <Emphasis Type="Italic">N</Emphasis>-methylaniline over molecular sieve catalysts

The preparation of N-methylaniline in two various processes: alkylation of aniline with methanol and hydroalkylation of nitrobenzene with methanol has been studied. Bifunctional molecular sieves containing metal copper as the hydrogenating component and zeolites BEA, MOR, MFI, FAU (Y) and mesoporous material MCM-41 as an alkylating component were used as catalysts. It has been shown that the modification of samples with copper nitrate increases the number of Lewis acid sites and decreases the number of Brønsted acid sites as copper embeds into cation exchange positions. It has been determined that the catalyst modification with copper increases the activity and enhances the selectivity towards N-alkylated products.     

用苯胺和甲醇在β沸石催化剂上合成N,N-二甲基苯胺

对苯胺和甲醇在β沸石催化剂上合成N ,N -二甲基苯胺 (N ,N -DMA)进行了研究。考察了反应温度、液态进料空速对催化剂活性和选择性的影响 ,对催化剂进行了 80 0h的寿命实验。实验证明 ,在n(苯胺 ) /n(甲醇 ) =1/3时 ,反应的最佳反应温度 2 40～ 2 5 0℃ ,最佳进料空速 0 5h- 1 。在 80 0h寿命实验过程中 ,苯胺的单程转化率达 99%(平均值 )以上 ,N ,N -DMA的选择性在 86 %以上 ,N -甲基苯胺 (N -MA)与N ,N -DMA的选择性在 95 %以上     

Synthesis and investigation of ZSM-5 zeolite-based catalysts for benzene alkylation with ethylene

A catalyst for alkylation of benzene with ethylene to ethylbenzene has been prepared by mixing 70% H⁺-ZSM-5 zeolite having a silica ratio of 30 with 30% pseudoboehmite followed by shaping granules, their drying, and calcining for 6 h at 650°C in air. A part of the catalyst has been treated by steaming with 100% steam at 600°C for 3 h. The physicochemical and catalytic properties of catalyst samples have been studied. The catalysts have been tested in a laboratory setup in the temperature interval of 380–450°C at 2.5MPa, a benzene space velocity of 15 h^?1, and a benzene/ethylene molar ratio of 7: 1. The properties of EBEMAX-1, an imported analogue of the catalysts have been studied under the same conditions. It has been found that the synthesized catalysts are not inferior to the imported sample in the catalytic properties.     

Biodiesel production from Sesamum indicum L. seed oil: An optimization study

Transesterification of Sesamum indicum L. oil was carried with methanol in the presence of sodium methoxide and the parameters affecting the reaction; vegetable oil/methanol molar ratio, catalyst concentration, reaction temperature and time were fully optimized by employing Central Composite Design method (CCD). A quadratic polynomial was developed to predict the response as a function of independent variables and their interactions and only the significant factors affecting the yield were fitted to a second-order response surface reduced 2FI model. At the optimum condition of 1:6 oil/methanol molar ratio, catalyst concentration of 0.75% and reaction time of 30 min, biodiesel yield of 87.80% was achieved. The selected fuel properties were within the range set by ASTM and EN bodies.     

甲醇气相羰基化非铑非卤素新催化体系研究Ⅲ.硫化的单组分Mo/C催化剂制备及羰化性能

采用硫化铵溶液硫化法制备的Mo/C催化剂经还原活化后具有很高的甲醇气相羰化活性与选择性。最佳的催化剂制备条件为 :Mo/S摩比为 1 /4、氢气还原温度为 450℃。最佳的羰化反应工艺条件为 :反应温度 2 80℃ ,CH3OH/CO进料摩比为 1 /2 ,CO的GHSV为 450 0L/(kgcat·h) ,此时甲醇转化率达 45 2 % ,醋酸甲酯选择性为77 8% ,产物时空收率高达 1 9 2 3mol/(kgcat·h)。     

Synthesis and gas separation properties of metathesis poly(5-ethylidene-2-norbornene)

High molecular weight metathesis poly(5-ethylidene-2-norbornene) (PENB) has been synthesized in the presence of the 1st generation Grubbs catalyst at a high monomer/catalyst ratio (3000/1 and higher). The yields of the corresponding polymer have been more than 90% at all monomer/catalyst ratios and molecular weights (M _w ) of PENB have been higher than 3 × 10⁵. The gas permeability of different gases (He, H₂, O₂, N₂, CO₂, and CH₄) through PENB films has been studied, and diffusivity and selectivity coefficients have been determined. It has been found that PENB is more permeable than unsubstituted metathesis polynorbornene and cycloalkyl-substituted polynorbornene dicarboximides, but it is less permeable than some Si-containing polynorbornenes. Despite the fact that PENB is more permeable than metathesis polynorbornene and cycloalkyl-substituted polynorbornene dicarboximides, it is close to these polymers in ideal selectivities for some gas pairs.     

Effect of operating conditions on alkylation of toluene with methanol

P-xylene (PX) is widely used as a raw material of synthesis of terephthalic acid (PTA) and polyester. With the demand of PTA and polyester, PX is demanded eagerly. The process for preparing PX through alkylation of toluene with methanol has been concerned widely. In an experiment HZSM-5/Al₂O₃ catalyst was prepared by loading pseudoboehmites on HZSM-5. The strength of B acid is adjusted, so side reactions can be controlled effectively. The optimum operating conditions are that molar ratio of toluene to methanol is 2.0, reaction temperature is 410°C, carrier gas flow is 7 mL/min, and WHSV is 1.0 h^?1 by investigating the effect of operating conditions on toluene conversion and PX selectivity. Toluene conversion and PX selectivity are up to 46.2% and 68.07%, respectively, under the optimum operating conditions.     

Transformations of diphenyl sulfide and diphenylamine on aluminum chloride

Thianthrene has been synthesized by reacting diphenyl sulfide with AlCl₃ in heptane at 98°C for 8 h at a diphenyl sulfide: AlCl₃ molar ratio of 2: 1; the thianthrene yield is 58%. The reaction mechanism proposed previously has been confirmed by quantum-chemical calculations; the reaction is characterized by a low negative value of Gibbs free energy, a low heat of reaction, and a high activation energy of the first step. Diphenyl ether and diphenylamine do not enter the test reaction because of low nucleophilicity of the heteroatoms; diphenylamine dimerizes under the reaction conditions to form N,N′-diphenylbenzidine.     

Ethylene oligomerization over chromium(III) complexes with pyrrole derivatives

The effect of the nature of a chromium(III) coordination compound and various substituted pyrrole ligands on ethylene oligomerization in the presence of a Cr(III) complex–pyrrole ligand (L)/AlEt₃ catalyst system (CS), where Cr(III) is Cr(EH)₃, Cr(асас)₃, or CrCl₃(THF)₃ and L is pyrrole, 2-phenylpyrrole, 2-formylpyrrole, N-methylpyrrole, or N-vinyl-2-phenylpyrrole, has been studied. It has been shown that the most significant effect on the behavior of the CS is exerted by the nature of the ligand involved in the formation of the CS. The acid–base properties of the employed ligands have been determined by quantum-chemical calculations. The data obtained have revealed that selectivity of the catalyst system depends on the ligand basicity.     

High operative heterogeneous catalyst in biodiesel production from waste cooking oil

Our work aims to produce a new catalyst that was a highly operative in the production of biodiesel from waste cooking oil WCO. A heterogeneous solid acid catalyst (RS-SO₃H) was prepared by fast pyrolysis of rice straw, then it was followed by a sulfonation process. It was formed by using concentrated sulfuric acid. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed that the chemical structure consists of sheets of amorphous carbon with hydroxyl and carbonyl (OH and COOH) groups as well as high density of SO₃H. The surface area of RS–SO₃H and the average pore size were characterized by scanning electron microscopy (SEM) and surface area analyzer. The results of Thermogravimetric analysis (TGA) showed that RS–SO₃H has favorable thermal stability. Conventional energy sources were exhausted. So, we examined the catalyst activity on developing alternative energy resources, It became more imperative and environment friendly. WCO is attracting increased attention in the biodiesel production by transesterification process. The factors affecting the transesterification process include reaction time and temperature, catalyst concentration and methanol: oil molar ratio, were studied. The maximum mass yield of biodiesel extended to 90.37%. The content of fatty acid methyl ester (FAME) is around 97.71 wt%, conversion efficiency% of raw material reached 90.38 wt% and %free fatty acid (%FFA) conversion was 91.1% at optimum conditions: 10 wt% catalyst using methanol: oil molar ratio (20:1) at 70 °C for 6 h. The FAME content% was determined by gas chromatography (GC). The physicochemical properties of the biodiesel produced are close to the commercial diesel and the ASTM standards biodiesel D6751. The reusability of the used catalyst indicated that the catalyst was highly operative in production biodiesel. Where % conversion efficiency of raw oil under optimized conditions decreased from 90.37 to 88.56% after 8 cycles. The %FFA conversion was constant around 91.1% until 7 runs then it decreased.     

Product distribution and catalytic performance of nano-sized H-ZSM-5 zeolites in the methanol-to-aromatics (MTA) reaction

A study of the effect of SiO₂/Al₂O₃ molar ratio on the activity and selectivity of H-ZSM-5 catalyst in the reaction of methanol to aromatics (MTA) has been carried out in this work. Aluminosilicate zeolite (ZSM-5) zeolites with different SiO₂/Al₂O₃ molar ratios were successfully synthesized by the hydrothermal method. The SiO₂/Al₂O₃ molar ratio of the prepared ZSM-5 zeolite particles could be easily controlled by changing the ratio of tetraethylorthosilicate to aluminum nitrate nonahydrate. The effect of SiO₂/Al₂O₃ molar ratio on the activity of nano-sized H-ZSM-5 zeolites in the MTA reaction was studied. The H-ZSM-5 zeolite catalyst with low SiO₂/Al₂O₃ molar ratios shows remarkable selectivity toward aromatics and benzene, toluene, and xylene (BTX) in the MTA reaction.     

Statistical optimization of biodiesel production from sunflower waste cooking oil using basic heterogeneous biocatalyst prepared from eggshells

A statistical design of experiments DOE was applied to investigate biodiesel fuel BDF production process from sunflower waste cooking oil SWCO using heterogeneous bio-catalyst produced from eggshells ES. It was based on 3 level D-optimal design involving as factors methanol:oil M:O molar ratio, catalyst concentration (wt%), reaction time (min) and mixing rate (rpm). Twenty runs were carried out. A predictive linear interaction model has been correlated finding out how significant the effects of these variables are in practice. LINGO software was used to find out the optimum values of the aforementioned variables for enhancing the process. According to the results obtained, the most dominant positive factor influencing the response variable (% BDF yield) was M:O molar ratio followed by catalyst concentration (wt%) and mixing rate in a decreasing order while the reaction time showed to have a negative effect on the yield. The maximum BDF yield (98.8% and 97.5%, predicted and experimental, respectively) was obtained at M:O 6:1 M ratio, catalyst concentration 3 wt%, reaction time 30 min, mixing rate 350 rpm and 60 °C. Also response surface methodology RSM has been applied to study the interactive effects of independent variables on BDF yield. It was found that, the interaction between M:O and catalyst concentration (wt%) has more significant effect than interaction between other variables. The activity of the produced bio-catalyst was comparable to that of chemical CaO and immobilized enzyme Novozym 435. All the physicochemical characteristics of the produced BDF using the prepared bio-catalyst and its blends with petro-diesel fuel PDF are completely acceptable and meet most of the required standard specifications.     

低温高活性甲醇水蒸气重整制氢催化剂的研究

研究了Cu/La2 O3 /ZrO2 基催化剂在甲醇水蒸气重整制氢反应中的反应活性、选择性及其还原行为 ,并考察了反应条件 (温度、水醇比、液体空速 )对活性和选择性的影响。结果表明 :Cu/La2 O3 /ZrO2 基催化剂在甲醇水蒸气重整制氢反应过程中显示出较好的反应活性和高的选择性。在常压、反应温度 190～ 2 40℃、液体空速为 1 0～ 3 0h-1和水醇摩比为 1～ 3 0的反应条件下 ,甲醇转化率随着反应温度的升高而增大 ,重整产物中CO含量有所增加 ;提高水醇比有利于提高甲醇转化率 ,同时可降低重整产物中CO含量 ;甲醇转化率随着液体空速的增加有所降低 ,而重整产物中CO含量也有所降低。在Cu/La2 O3 /ZrO2 基催化剂上 ,甲醇重整反应和水 汽变换反应有可能同时进行     

环氧乙烷氢甲酯化制3-羟基丙酸甲酯工艺条件和动力学研究

以环氧乙烷、甲醇和CO为原料,Co2(CO)8为催化剂,3-羟基吡啶为配位体,合成3-羟基丙酸甲酯。考察了反应温度、压力、环氧乙烷浓度、催化剂和配位体添加量等对环氧乙烷转化率和目的产物选择性的影响,得到的较适宜反应条件为:温度70℃,压力7.0MPa,n(环氧乙烷)/n(主催化剂)=100/1;n(配体)/n(主催化剂)=6/1;n(甲醇)/n(环氧乙烷)=6/1。在该条件下环氧乙烷转化率接近100%,对3-羟基丙酸甲酯的选择性达到93%。反应中环氧乙烷浓度对时间的微分与其浓度成正比,呈一级关系。用阿仑尼乌斯方程求得的反应速率常数为(0.2～0.61)×10-3min-1,表观活化能为72.75kJ·mol-1,指前因子为ko=4.97×107min-1。     

异戊烯酸甲酯催化合成新工艺

实验以异戊烯酸和甲醇为原料,732型强酸性阳离子交换树脂为催化剂,采用甲醇外循环吸附除水工艺合成异戊烯酸甲酯。考察了醇酸摩尔比、催化剂用量和反应时间对酯化反应的影响。较佳工艺条件为:n_0(甲醇):n_0(异戊烯酸)=2.4:1,催化剂用量22 g/mol,反应时间16 h,酯化率达99.57%。     

Etherification Performance of Transition Metals Modified β-Zeolite Catalyst

Abstract

The etherification experiment for FCC light gasoline on transition metals modified Hβ zeolite was studied in a fixed-bed reactor. The effect of preparation condition of catalyst on the catalyst's activity, stability, and the effect of reaction temperature, methanol/tert-olefin molar ratio, and liquid hour space velocity on the etherification reaction were discussed. The experimental results showed that the different metals modified Hβ zeolite had different etherification performances. And the conversion of tertiary carbon-olefins of the molybdenum modified Hβ zeolite, which was loaded 3%, was higher 6.0% than the Hβ zeolite. The optimal reaction conditions were temperature 70–80°C, liquid hour space velocity 1.0 h^?1 and methanol/tert-olefin molar ratio 1.05. The modified Hβ zeolite catalysts possessed favorable prospect for its higher stability.     

二氧化氮为硝化剂的苯硝化反应

以溶胶-凝胶法制备的负载型磷钨杂多酸为催化剂,分别在常压和加压条件下,优化了NO_2代替硝酸作为硝化剂的苯液相硝化反应条件。对于常压反应,在m(催化剂):m(苯)=1:12、NO_2气体流速为10 mL/min、O_2流速为5 mL/min、反应时间为8 h、反应温度为60℃的件下,硝基苯收率为29.5%。对于加压反应,适宜的反应条件为:n(NO_2)n(苯)=2.5:1,w(催化剂)=3.5%,O_2初始压力1.0 MPa,反应温度90℃,反应时间6 h。在此条件下,硝基苯收率为41.8%。     

Activity and stereospecificity of cobalt-methylaluminoxane catalyst in butadiene polymerization

Butadiene polymerization in aliphatic and aromatic solvents mediated by a preliminarily formed catalyst consisting of cobalt 2-ethylhexanoate, methylaluminoxane, and diene was studied. It was shown that the catalyst was active at a molar ratio of methylaluminoxane: cobalt: diene = 75?200:1:20, yielding high-molecular-mass polymers (intrinsic viscosity, 1.8–2.7 dl/g) containing at least 98% cis-1,4-units. Preliminary formation of the catalyst was found to increase its activity in butadiene polymerization at a low Al:Co ratio. In this case, the catalyst retains its high stereospecificity (the amount of cis-1,4-units in the polymer reaches 98% and more) independently of the nature of the solvent used for polymerization.     

负载固体酸催化豆油制备生物柴油的研究

以负载固体酸为催化剂,甲醇和大豆油为原料,合成了生物柴油。在单因素的基础上,应用Box-Behnken中心组合原理,对醇油量比,催化剂用量,反应时间三个因素进行了三水平的实验设计。通过响应面分析,确定最佳工艺为:醇油量比7∶1,m(催化剂)/m(豆油)为5.95%,反应时间3.75h。此条件下生物柴油产率为96.62%。多次使用后,催化剂仍表现出较好的催化活性。并利用XRD、FT-IR光谱表征了催化剂的物相和产品结构,用气相色谱-质谱联用法对产品进行了定性和定量分析。     

MAF固体碱催化剂催化合成丙二醇甲醚

研究了甲醇与环氧丙烷在固体碱催化剂MAF存在下非均相合成丙二醇甲醚的过程。在反应温度为120～130℃、催化剂用量(质量分数)为0.20%～0.30%、甲醇与环氧丙烷摩尔比为3/1～5/1的反应条件下,环氧丙烷的转化率在98％以上,丙二醇甲醚的选择性达95％,收率达93％,产品中伯醚的选择性为92％～93％。实验发现,该固体碱催化剂使用后无须任何处理,可重复使用,是一种稳定性好、选择性高的环境友好催化剂。