在Pt/Al2O3催化剂上苯的内扩散对负0.9级动力学的影响

在Pt/Al₂O₃催化剂上用外循环反应器研究了内扩散对苯完全氧化动力学的影响,当用30～40目(即0.45～0.60mm)催化剂时反应在动力学区域进行.若O₂过量时则动力学区域苯的完全氧化可用-0.9级速率方程描述.当催化剂粒径增至φ6×5mm时,反应在内扩散区域进行并变为一0.1级反应.催化剂有效因子η在0.24～0.12之间.在同一温度下,η_实验随苯分压p_苯的增加而增大;而p_苯相近时,η_实验则随温度的升高而减小.动力学区域的反应活化能为55.5kJ/mol,内扩散区域的反应活化能为34.9kJ/mol,其值约为动力学区域的活化能与苯分子扩散活化能的算术平均值.     

在Mo-Bi-Ce/SiO_2催化剂上内扩散对甲醇氧化制甲醛Redox机理动力学的影响

在30—40目的Mo-Bi-Ce/SiO_2催化剂上,甲醇氧化制甲醛反应在动力学区域进行时,其动力学服从Redox 机理方程。当催化剂颗粒增大至2mm 时,内扩散对甲醇氧化制甲醛的反应影响严重,催化剂的有效因子在0.47—0.85之间,从Redox 机理方程出发,对此值进行了内扩散影响的理论分析。内扩散对Redox 机理方程的反应活化能的影响服从(15)式,并从实验上得到证实。用动力学方法测定了甲醇的扩散系数。     

板状镍催化剂上氨分解和氨部分氧化制氮氢气的研究

研制了一种 Ni/Al₂O₃多孔板状催化剂.该催化剂在反应温度高于750℃,氨分解率高于99.5%时,允许反应空速达10000—40000h^-1.用该催化板组装的反应器可采用内加热形式,和一般的外加热反应器相比可节约能耗约30%.在催化板上氨分解的经验动力学方程是γ=kp²NH₃,表观活化能为153.0kJ/mol.将该催化剂用于氨部分氧化时,在空气和氨比为1.0—1.7,680—750℃,氨空速10000—40000h^-1条件下,在氨点火后无外加能源情况下,能制得含氢30～43%,残氧小于0.1%的氮氢混合气,氨的转化率>99.5%,连续250小时反应表明,催化剂活性稳定.宏观动力学研究得出,反应对氨呈零级,表观活化能为37.2kJ/mol.     

气固相法合成的Ti—ZSM—5催化剂上苯乙烯氧化应的宏观动力学

采用TiCl4气固相同晶取代法制得的Ti-ZSM-5作催化剂,对H2O2氧化苯乙烯反应的宏观动力学进行了研究,考察了催化剂、苯乙烯和H2O2用量及反应温度对苯乙烯氧化反应速率的影响。结果表明,催化剂Ti-ZSM-5和底物苯乙烯对苯乙烯氧化反应速率的贡献均为一级,而H2O2为1／2级;苯乙烯氧化反应的表观活化能Ea＝48.14kJ/mol。当以丙酮为溶剂,在n(PhCH:CH2)/n(H2O2)=7.91,催化剂用量为20g/L,反应温度为343K的条件下,反应360min时,苯乙醛选择性和H2O2利用率分别可达91.9%和88.6%。     

Ti-MWW催化氯丙烯环氧化反应动力学行为

以Ti-MWW分子筛为催化剂,以H2O2为氧化剂,系统研究了氯丙烯环氧化反应的动力学行为.结果表明,该反应速率与Ti-MWW分子筛的用量成正比,是1级反应.当H2O2浓度小于0.67 mol/L时,环氧化反应为1级反应;大于2 mol/L时,为0级反应.随着氯丙烯浓度的增加,环氧化反应级数从1级向0级转变;且只有当其浓...     

负载双核茂金属催化剂催化乙烯聚合反应动力学研究

以SiO2为载体,制备了负载的双核茂金属[（η5-C5H5）Zr Cl2]2[μ,μ-（SiMe2）2（η5-allyl C5H2）2]/MAO/SiO2催化剂,以己烷为溶剂进行了淤浆条件下乙烯聚合反应,研究了扩散因素、乙烯聚合压力和聚合温度对乙烯淤浆聚合动力学参数的影响,测定了聚合反应级数和表观活化能,采用动力学和相对分子质量法计算了负载催化剂的活性中心浓度,并对链增长速率常数等动力学参数进行了计算.结果表明,以负载双核茂金属催化剂催化乙烯淤浆聚合反应速率对单体浓度呈1.11级依赖,反应活化能Ea为72.47 kJ/mol,活性中心浓度C＊为0.33 mol/mol,链增长速率常数Kp为1.06×106L.（mol.h）-1.     

银催化剂上丁二烯环氧化宏观反应动力学的研究

考察了在Ba-Cs-Cl-Ag/α-Al2O3上以空气为氧化剂的丁二烯气相环氧化反应条件对催化剂性能的影响.宏观动力学实验结果表明,依据Langmuir-Hinselwood机理推测的动力学表达式与实验结果吻合较好,幂函数型的动力学表达式给出了在低丁二烯分压下,丁二烯的反应级数为1.9,O2的反应级数为1.1.丁二烯转化、生成乙烯基环氧乙烷及生成CO2的表观活化能分别为55.4 kJ/mol、 54.8 kJ/mol和64.6 kJ/mol.     

ZnCl2/粘土-SA01催化合成二苯甲烷反应动力学研究

在ZnCl2/粘土-SA01催化剂上合成了二苯甲烷,考察了负载量、苯/苄基氯摩尔比、催化剂用量、反应温度和时间对该反应的影响,研究了以ZnCl2/粘土-SA01为催化剂合成二苯甲烷的反应动力学,为探讨其反应机理和研究烷基化反应动力学提供了依据.结果表明,温度在303-318K时,本征动力学方程为r=k[ZnCl2/粘土-SA01]0.8[C6H6][C6H5CH2Cl],属二级反应,表观反应活化能为88.6kJ/mol;在328-353K时,其本征动力学方程为r=k[ZnCl2/粘土-SA01]0.1,反应属零级反应,表观活化能为52.8kJ/mol.     

Redox机理动力学内扩散影响的特征

在Pb_0.88Bi_0.06La_0.02Mo/SiO₂催化剂上,反应在动力学区域进行时,甲醇氧化制甲醛服从Redox机理动力学方程:r=(k₁k₂P甲醇Po₂)/(0.5k₁P甲醇+k₂Po₂)当催化剂颗粒增大至3mm时,内扩散影响严重,催化剂有效因子在0.38-0.73之间,其内扩散区域的速度方程为r内=(Do₂/RTKL)2φ_M[K(Po₂-Po_2.o)-ln(1+Kpo₂/1+Kpo_2.o)]^1/2测定了反应受O₂内扩散控制时的反应活化能E内为74.5kJ/mol。     

气固相法合成的Ti-ZSM-5催化剂上苯乙烯氧化反应的宏观动力学

 采用TiCl4气固相同晶取代法制得的Ti－ZSM－5作催化剂,对H2O2氧化苯乙烯反应的宏观动力学进行了研究,考察了催化剂、苯乙烯和H2O2用量及反应温度对苯乙烯氧化反应速率的影响．结果表明,催化剂Ti－ZSM－5和底物苯乙烯对苯乙烯氧化反应速率的贡献均为一级,而H2O2为1／2级;苯乙烯氧化反应的表观活化能Ea＝48．14kJ／mol．当以丙酮为溶剂,在n（PhCH∶CH2）／n（H2O2）＝7．91,催化剂用量为20g／L,反应温度为343K的条件下,反应360min时,苯乙醛选择性和H2O2利用率分别可达91．9％和88．6％．     

己烷临氢异构化的复杂反应动力学网络

应用连续微反-色谱装置, 在反应温度为210-260℃, 反应压力为1.96MPa,H~2/乙烷摩尔比为8的条件下, 研究了己烷的五个异构体在载钯氢型丝光沸石催化剂上的临氢异构化反应动力学。结果表明, 在总压和H~2/己烷摩尔比恒定条件下,己烷的异构化动力学行为可以用拟一级复杂反应网络来描述。求取了该复杂反应网络中每一步异构化反应的速率常数, 各步反应的活化能在88.2-228kJ·mol^-^1之间。     

Sodium chloride-catalyzed oxidation of multiwalled carbon nanotubes for environmental benefit

A sodium chloride (NaCl) catalyst (0.1 w/w %) lowers the oxidation temperature of graphitized multiwalled carbon nanotubes: MWCNT-20 (diameter: 20-70 nm) and MWCNT-80 (diameter: 80-150 nm). The analysis of the reaction kinetics indicates that the oxidation of MWCNT-20 and MWCNT-80 mixed with no NaCl exhibits single reaction processes with activation energies of E(a) = 159 and 152 kJ mol(-1), respectively. The oxidation reaction in the presence of NaCl is shown to consist of two different reaction processes, that is, a first reaction and a second reaction process. The first reaction process is dominant at a low temperature of around 600 degrees C, while the second reaction process becomes more dominant than the first one in a higher temperature region. The activation energies of the first reaction processes (MWCNT-20: E(a1) = 35.7 kJ mol(-1); MWCNT-80: E(a1) = 43.5 kJ mol(-1)) are much smaller than those of the second reaction processes (MWCNT-20: E(a2) = 170 kJ mol(-1); MWCNT-80: E(a2) = 171 kJ mol(-1)). The comparison of the kinetic parameters and the results of the spectroscopic and microscopic analyses imply that the lowering of the oxidation temperature in the presence of NaCl results from the introduction of disorder into the graphitized MWCNTs (during the first reaction process), thus increasing the facility of the oxidation reaction of the disorder-induced nanotubes (in the second reaction process). It is found that the larger nanopits and cracks on the outer graphitic layers are caused by the catalytic effect of NaCl. Therefore, the NaCl-mixed samples showed more rapid and stronger oxidation compared with that of the nonmixed samples at the same residual quantity.     

Macro-kinetics of styrene oxidation catalyzed by Co<Superscript>2+</Superscript>-exchanged X

The macro-kinetics and pathway of styrene oxidation catalyzed by Co²⁺-exchanged X, using O₂ as oxidant, were investigated. The effects of external diffusion, internal diffusion, the styrene concentration, O₂ pressure, the catalyst concentration and the reaction temperature on the styrene oxidation reaction rate were examined. The results showed that the reaction rate of styrene oxidation was 0.19 order with respect to the styrene concentration, 0.64 order with respect to O₂ pressure, and zero to first order with respect to the different catalyst concentration. The calculated activation energy for this reaction was 13.79 kJ/mol. On the other hand, the three products in the styrene oxidation reaction were, respectively, used as the reactant to examine the reaction pathway of styrene oxidation. The results revealed that styrene oxidation reaction occurred as two parallel reactions. One was the production of styrene oxide and the other was the production of benzaldehyde and formaldehyde with former partially oxidized to benzoic acid and the latter mostly oxidized to O₂ and H₂O. Published in Russian in Kinetika i Kataliz, 2009, vol. 50, No. 2, pp. 212–217. The article is published in the original.     

甲苯在HCeY沸石上的脉冲反应动力学

在2.1-3.1kg压力下,探索了在HCeY沸石催化剂上取得脉冲反应动力学数据的条件。实验结果表明,在521-568℃温度区间、30-60ml/min流速范围内,甲苯在HCeY沸石上的催化反应以脱烷基为主,近似符合一级反应动力学特征。求得表观活化能为71.5kJ/mol;吸附热34.9KJ/mol;表面反应活化能为106.4kJ/mol。     

KINETIC STUDIES ON METHANE REFORMING WITH CARBON DIOXIDE

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Oxide talum-containing catalysts of ozone decomposition and methane oxidation

The oxidation of manganese ions is shown to occur in ozone decomposition on manganese-containing catalyst, leading to the deactivation of a sample. The structure of the iron-containing catalyst does not change, ensuring its high stability during ozone decomposition in a dry gas flow at room temperature, conducted in the region of inner diffusion with an activation energy of 15.5 ± 0.7 kJ/mol. The presence of manganese cations in the intermediate stages of reduction is found to increase their activity in the reaction of deep methane oxidation.     

Kinetics of oxidation of phenol with manganese dioxide

The kinetics of oxidation of phenol with manganese dioxide at pH 5.5±0.5 were studied. In the temperature range from 393 to 323 K the reaction is of second order, and it occurs in the kinetic mode with an energy of activation of 42.0 kJ/mol. In the temperature range from 333 to 353 K the reaction follows first-order equation and is controlled by external diffusion; the energy of activation is equal to 6.65 kJ/mol. The oxidation products are hydroquinone and 1,4-benzoquinone, the fraction of the latter being less than 10 mol %.     

Thermal Degradation Kinetics of N,N＇-Di（diethoxythiophosphoryl）-1,4-phenylenediamine

The non-isothermal degradation kinetics of N,N＇-di（diethoxythiophosphoryl）-1,4-phenylenediamine in N2 was studied by TG-DTG techniques.The kinetic parameters,including the activation energy and pre-exponential factor of the degradation process for the title compound were calculated by means of the Kissinger and Flynn-Wall-Ozawa（FWO）method and the thermal degradation mechanism of the title compound was also studied with the Satava-Sestak methods.The results indicate that the activation energy and pre-exponential factor are 152.61 kJ/mol and 9.06×101 4s -1with the Kissinger method and 154.08 kJ/mol with the Flynn-Wall-Ozawa method,respectively.It has been shown that the degradation of the title compound follows a kinetic model of one-dimensional diffusion or parabolic law,the kinetic function is G（α）=α2and the reaction order is n=2.