TS-1催化苯羟基化制苯酚的本征动力学

TS-1分子筛催化苯羟基化法制苯酚是一种绿色工艺路线。对以TS-1为催化剂苯与过氧化氢反应制苯酚的本征动力学进行了研究。考察了搅拌速度、苯浓度、过氧化氢浓度以及反应温度等因素对苯酚初始生成速率的影响,并采用幂函数方程进行实验数据拟合。结果表明,在消除内外扩散影响的条件下,反应对于苯、过氧化氢的反应级数分别为0.62和0.55,反应的活化能为101.31 kJ/mol。依据上述结果建立了反应的本征动力学方程,并对模型进行验证,结果显示模型计算得到的苯酚初始生成速率与实验值的平均相对偏差为6.81%,吻合较好。研究得到的动力学模型为TS-1催化苯羟基化-膜分离耦合制备苯酚的条件优化及过程开发提供依据。     

FTH-2催化剂上重芳烃烷基转移反应动力学研究

对在FTH-2催化剂上重芳烃烷基转移反应的本征动力学进行了研究。在排除内外扩散影响后,结合变空速实验确定反应的主反应,并进行动力学实验,建立动力学模型,采用常微分方程的参数估值法进行参数估值,利用Matlab编程对参数进行优化计算,并检验模型参数,确定苯与重芳烃的烷基转移反应的本征动力学方程为:r_1=1.3027×10~4exp(-6.927/RT)·y_(TIPB)~(0.73)·y_B~(2.41)·y_(IPB)~(-0.64)     

醋酸异丙酯催化加氢制双醇反应网络及动力学研究

以羧酸酯为原料催化加氢同时制备两种不同(或相同)的醇是一条绿色清洁的原子经济工艺路线。研究采用自主开发的20Cu-8Zn O/Si O2-5K2O催化剂用于醋酸异丙酯加氢制备乙醇和异丙醇的反应体系。通过对催化剂各组分作用分析及主副反应剖析,结合反应产物组成及分布,提出了反应机理和反应网络。采用三段控温的固定床反应器,消除内、外扩散影响后在反应压力5 MPa、氢气与醋酸异丙酯进料摩尔比为30~60、醋酸异丙酯进料流量0~0.20 m L?min?1及反应温度250~280℃的条件下,实测了醋酸异丙酯加氢反应的本征动力学数据;在合理简化反应网络的基础上,建立了本征动力学模型,拟合了模型参数,并进行了模型参数物理意义分析和模型适定性检验。结果表明:当氢酯进料摩尔比≥30,催化剂粒径≤0.30 mm,内、外扩散阻力均已消除;以Matlab软件中非线性最小二乘法拟合结果与动力学实验测定数据吻合良好;在实验范围内,建立的本征动力学模型对醋酸异丙酯加氢制备乙醇和异丙醇反应高度适定。     

对溴苯酚歧化异构化反应动力学

测定了在 15 0～ 180℃范围内对溴苯酚歧化异构化反应的动力学数据 ,提出了对溴苯酚的歧化异构化反应为一级不可逆平行反应 ,并选用 Powell法和定步长龙格库塔法相结合的数学方法拟合实验数据 ,估算了动力学模型参数 ,模型计算值与实验值拟合良好     

Ag/MIL-101催化剂还原对硝基苯酚反应动力学

采用双溶剂浸渍法制备得到了粒径为1.9nm±0.6nm高分散性的Ag/MIL-101催化剂。考察了该催化剂在过量NaBH₄存在下,还原对硝基苯酚生成对氨基苯酚反应中的催化性能。本文通过研究催化剂浓度、底物浓度和温度对催化活性的影响,获得不同条件下的表观反应速率常数k_app,采用Langmuir-Hinshelwood吸附反应模型对所得动力学数据进行拟合,获得本征反应速率常数k,底物吸附常数K_4-NP和K_BH4,底物吸附焓、熵以及真实活化能E_A,k等热力学参数。研究表明,诱导时间t₀直接与该反应速率控制步骤的反应速率常数k有关。     

FX-01催化剂上苯与丙烯烷基化反应过程研究(Ⅰ)——反应动力学

对FX-01沸石催化剂上苯与丙烯烷基化反应进行了研究,得出了气液固三相催化反应的本征动力学模型.动力学实验是在消除了内扩散、外扩散影响的条件下,在高压釜间歇反应器中进行的, 采用常微分方程的参数估值法进行参数估值,得到本征动力学方程.     

改性竹炭对4-硝基苯酚的吸附行为研究

采用硝酸对竹炭进行改性,考察了改性竹炭对水溶液中4-硝基苯酚的吸附热力学和动力学特性。结果表明,与原竹炭相比,硝酸改性竹炭的比表面积、孔容及对4-硝基苯酚的吸附量显著提高。在实验条件下,动力学过程用二级吸附动力学模拟具有很好的线性相关性,通过二级吸附模型计算出的平衡吸附量与实验值相符。改性竹炭对4-硝基苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述,相关性都较好,但更符合Langmuir公式。求得热力学参数ΔH=28.36 kJ/mol,ΔS=168.88 J/(K.mol),ΔG分别为-19.41(10℃)、-22.86(30℃)、-26.16(50℃)kJ/mol,表明改性竹炭对4-硝基苯酚的吸附是吸热、自发的过程,以物理吸附为主。     

粉末活性炭对苯酚废水的吸附研究

文章研究了粉末活性炭处理苯酚废水的方法。系统考虑了粉末活性炭用量、pH、反应时间和温度等重要因素。实验结果表明:在室温下,活性炭用量为0.1 g,废水pH为6.0,反应时间为30 min,苯酚去除率可达98.4%。从动力学和热力学角度分析吸附原理,其动力学更好地符合Lagergren伪二级反应动力学模型,热力学较好的符合Langmuir等温线。     

碳酸二甲酯与苯酚反应动力学及工艺研究进展

碳酸二苯酯是一种重要的化工原料中间体,可用于合成多种有机化合物和聚合材料。文章主要对碳酸二甲酯和苯酚酯交换法合成碳酸二苯酯的反应热力学特征、动力学和工艺进行了综述,文章重点分析了近年来酯交换反应动力学研究的现状及难点,并指出了动力学研究的发展方向;同时对酯交换反应一步法和二步法合成工艺进行了深入探讨,其中酯化-歧化二步法工艺因其高转化率和原料利用率而备受关注。     

乙烯在银催化剂上氧化本征动力学的研究

采用固定床恒温积分反应器，对YS-6型银催化剂进行乙烯氧化本征动力学研究。选择与工业应用接近的条件进行动力学实验，根据建立的动力学模型。用动力学试验数据采用双响应Marquardt法，以转化率，选择性为目标函数进行待定参数估值。确定待定参数，得到本征动力学方程，根据数学统计检验，文中所建立的模型残差分布合理。参数回归显著，能够反映YS-6型催化剂的反应特性。     

Mechanism and NaOH effect of polymer-supported catalyst: phosphazene reaction

The mechanism and NaOH effect of the substitution reaction of hexachlorocyclotriphosphazene, (NPCl₂)₃, with phenol to synthesize the poly(phenoxy)chlorocyclotriphosphazene were investigated by using triphase catalysis in an organic phase/alkaline solution. Four relationships between the ion-exchange reaction and organic reaction were presented and clarified by experimental result. The reaction behaviors varied with different particle sizes of resins. The reaction zone was not the whole resin, and occurred obviously at a shell of the resin when the resin was used larger particle size and higher degree of crosslinkage. The thickness of shell in the resin varied with different NaOH concentrations. The intrinsic reaction kinetics, particle diffusion and film diffusion had to be considered to explain this triphase reaction behavior. The performance of recycle fixed-bed reactor was also investigated.     

用阳离子交换树脂催化酯化合成乙酸异丙酯动力学研究

在间歇反应釜中,采用强酸型阳离子交换树脂(Amberlyst 15-Wet)作催化剂,在液-固两相体系中对乙酸异丙酯合成反应过程进行了研究,系统地考察了搅拌速度、催化剂粒径、温度、催化剂浓度、酸醇比对酯化反应速率的影响。同时通过拟均相动力学模型对反应过程进行了模拟,计算得到了相关的动力学参数。计算结果与与实验值吻合良好,能较好地描述乙酸和异丙醇合成乙酸异丙酯的酯化反应过程。     

以Pd/C为催化剂的松香加氢本征动力学

在温度403~433K,压力3.0～7.0MPa下,研究了以Pd/C为催化剂的松香催化加氢本征动力学,为工业反应过程的开发和操作提供了理论依据.通过减少催化剂粒度和提高搅拌转速,以消除内外扩散的影响,在松香加氢反应过程中,在线跟踪了反应物和产物浓度随反应时间的变化关系.根据实验数据,采用EVIEWS软件对10个可能的反应机理模型进行筛选,认为最可几的反应机理为松香中的主要成分枞酸分子不吸附,枞酸分子与催化剂表面上被吸附的氢原子进行反应,氢原子的吸附为控制步骤;其反应动力学方程为, 据此导出反应速率常数和吸附平衡常数分别为 (Hk =5.695exp((2498.5/T), bs =9.4(10(3exp(1920.8/T).     

Removal of pyridine derivatives from aqueous solution by activated carbons developed from agricultural waste materials

The paper investigates the ability of activated carbons developed from coconut shell to adsorb α-picoline, β-picoline, and γ-picolin from aqueous solution. The developed carbons are designated as SAC (activated carbon derived from coconut shells with out any treatment) and ATSAC (activated carbon derived from acid treated coconut shells). The carbons were, characterized and utilized for the sorption of α-picoline, β-picoline, and γ-picoline at different temperatures, particle size, pH and solid to liquid ratio. All the studies were performed by batch method to determine various equilibrium and kinetic parameters. The Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to best report the equilibrium isotherm data. The adsorption of α-, β-, and γ-picoline followed the pseudo-second order rate kinetics. On the basis of kinetic studies, various rate and thermodynamic parameters such as effective diffusion coefficients, activation energy and activation entropy were evaluated. It was concluded that in majority of cases, the adsorption is controlled by particle diffusion at temperatures 10° and 25 °C while at 40 °C it is controlled by film diffusion mechanism. Similarly at concentrations 25 and 50 mg/l the adsorption was governed by particle diffusion in most of the cases while at >50 mg/l it was film diffusion controlled. The overall capacity of ATSAC was higher than SAC. The sorption capacity of γ-picoline was found more followed by β-picoline and α-picoline.     

新型钴钼系耐硫变换催化剂本征动力学

采用等温管式积分反应器,在(550~750) K、(2.0~3.5) MPa和空速(15~30) L·(g·h)^-1条件下，对新型钴钼系耐硫变换催化剂进行变换反应本征动力学研究。建立了包含压力项的幂函数型动力学模型，根据实验测定数据，结合具有全局寻优能力微粒群算法和求解微分方程的龙格-库塔法，通过迭代寻优对变换反应动力学模型进行参数估计，获得高度显著、可信的动力学模型。结果表明，在催化剂上进行变换反应时，反应速率对CO组分分压变化的敏感性较低，H₂O组分分压对反应速率的影响较大，高汽气比下催化活性较高。     

封闭型异氰酸酯齐聚物及与PET反应性共混

合成了一系列由聚乙二醇、芳香族二异氰酸酯以及乙醇、异丙醇、苯酚组成的封闭型异氰酸酯齐聚物（ＴＩＯ）；应用差示扫描量热法、红外光谱、特性粘数测试等手段，表征了这些ＴＩＯ的解封闭特性，进而在哈克流变仪上进行聚对苯二甲酸乙二酯与ＴＩＯ反应性共混，初步研究了共混物的特性粘数和热性能。     

Eco friendly adsorbents for removal of phenol from aqueous solution employing nanoparticle zero-valent iron synthesized from modified green tea bio-waste and supported on silty clay

The present research investigated a novel route for the synthesis of nanoparticle zero-valent iron(NZVI) utilizing an aqueous extract of green tea waste as a reductant with ferric chloride. Also, the supported nanoparticle zerovalent iron was synthesized using natural silty clay as a support material(SC-NZVI). The NZVI and SC-NZVI were characterized by infrared spectroscopy(FTIR), scanning electron microscope(SEM), X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET), and zeta potential(ζ). The interpretation of the results demonstrated that the polyphenol and other antioxidants in green tea waste can be used as reduction and capping agents in NZVI synthesis, with silty clay an adequate support. Additionally, the experiments were carried out to explore phenol adsorption by NZVI and SC-NZVI. To determine the optimum conditions, the impact of diverse experimental factors(i.e., initial pH, adsorbent dose, temperature, and concentration of phenol) was studied. Langmuir, Freundlich,and Tempkin isotherms were used as representatives of adsorption equilibrium. The obtained results indicated that the adsorption processes for both NZVI and SC-NZVI well fitted by the Freundlich isotherm model. The appropriateness of pseudo_first_order and pseudo_second_order kinetics was investigated. The experimental kinetics data were good explained by the second-order model. The thermodynamic parameters(ΔH0, ΔS0, andΔG0) for NZVI and SC-NZVI were determined. The maximum removal rates of phenol at optimum conditions,when adsorbed onto NZVI and SC-NZVI, were found to be 94.8% and 90.1%, respectively.     

TS-1催化苯酚羟基化制苯二酚的本征动力学研究

采用苯酚直接羟基化联产邻、对苯二酚被认为是目前合成苯二酚的绿色工艺路线之一,但关于以TS-1分子筛为催化剂的本征反应动力学尚在研究中。文中借助高效液相色谱技术,研究了在TS-1分子筛催化下以双氧水直接氧化苯酚为苯二酚的本征反应动力学。结果表明,当搅拌器的转速大于380 r/min时,外扩散已基本消除,反应进入动力学控制区。该反应对于苯酚和羟基化试剂双氧水的反应级数为1.2和0.53,反应活化能为76.87 kJ/mol,反应指前因子为7.58×109mol0.73/(L0.73.min)。这可为TS-1催化-膜分离耦合制备苯二酚反应过程开发和工业反应器设计提供基础数据。     

Adsorption of Cr(VI) using thermally activated weed Salvinia cucullata

Cr(VI) removal studies were carried out by using activated carbon obtained from waste weed, Salvinia cucullata. Effects of various parameters, such as pH, contact time, temperature, adsorbate concentration, adsorbent dose and particle size of the adsorbent on percentage of adsorption were studied. The adsorption studies were carried out at an agitation speed of 600 rpm to minimize the film diffusion. The adsorption kinetics followed dual rate; it was fast during a first stage and then it was reduced. The equilibrium was achieved in 12 h. The kinetics increased with decrease in pH. Adsorbate and adsorbent concentration also influenced the kinetics. The adsorption process was endothermic in nature. The reaction kinetics followed pseudo-second-order kinetic equation. Empirical rate equation developed, which explained the effect of various adsorption parameters, was studied. Theoretical numbers of stages were calculated based on the results. Intra-particle diffusion was found to be the rate-controlling step. Optimization studies were also carried out to establish the upper and lower breakthrough points.