共查询到19条相似文献,搜索用时 62 毫秒
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采用干混法、浸渍法、溶胶凝胶法3种制备方法制备ZrO2/SiO2,在固定床微型反应器中进行催化剂的活性评价。通过溶胶凝胶法制备的ZrO2/SiO2对丁二烯选择性最高,达到64.77%。采用氨气程序升温脱附(NH3-TPD)、X射线衍射(XRD)、透射电镜(TEM)等手段对催化剂表面酸性以及表面结构进行了表征,结果表明锆在二氧化硅表面均匀分布有利于乙醇乙醛转化率以及对1,3-丁二烯选择性的提高,同时1,3-丁二烯的生成需要合适的酸性位。以溶胶凝胶法制备的ZrO2/SiO2为催化剂,对其制备条件进行了优化,得出最佳制备条件为焙烧温度650℃、硝酸浓度2mol/L、混合温度30℃。 相似文献
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环氧化液体丁二烯-苯乙烯共聚物的制备 总被引:1,自引:0,他引:1
采用阴离子聚合制备了线型和星型液体丁二烯-苯乙烯嵌段共聚物(LBSC)、含渐变段共聚物和无规共聚物。采用甲酸-H_2O_2原位法对上述LBSC进行了环氧化反应。考察了H_2O_2用量、环氧化反应时间和温度、相对分子质量、苯乙烯含量和序列结构等对LBSC环氧化反应的影响;研究了环氧化液体丁苯共聚物(ELBSC)偶联剂对聚丁二烯活性链末端偶联反应的影响。结果表明:控制H_2O_2用量可以得到环氧值可控的ELBSC,当H_2O_2与丁苯共聚物中聚丁二烯双键的摩尔比为0.6,反应时间在120 min,温度在50℃时可达到最大环氧值;随着ELBSC用量的增加,偶联效率逐渐增大,相对臂数逐渐减小,在环氧基团与锂的摩尔比为1.0时偶联效率最大。 相似文献
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1,3-丙二醇分批发酵动力学模型 总被引:4,自引:1,他引:4
在分批发酵中,研究了Klebsiella pneumoniae的生长、底物甘油消耗及1,3-丙二醇的产生特性. 基于Logistic方程和Luedeking-Piret方程,得到了描述1,3-丙二醇分批发酵过程的动力学模型及模型参数,该组模型能很好地拟合发酵过程,并在初始甘油浓度变化较大的范围内表现出很好的适用性. 同时,所建立的模型也基本反映了Klebsiella pneumoniae分批发酵过程的动力学特征. 基于分批发酵动力学模型,提出了以甘油为单一碳源时的底物流加策略,通过与其他流加策略条件下的发酵对比实验表明,通过基于动力学模型的流加策略可获得更高的1,3-丙二醇浓度及生产强度. 相似文献
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采用水热法制备了Bi2MoO6纳米片催化剂、共沉淀法制备了BiMoV0.15催化剂,在固定床反应器中研究了两种催化剂上丁烯氧化脱氢制丁二烯的本征动力学.采用幂函数模型对不同条件下测得的动力学数据进行了拟合,建立了本征动力学模型,并得到了活化能和反应级数等相关参数.结果表明:由于不同的反应温度区间拥有不同的速率控制步骤,... 相似文献
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《应用化工》2022,(10):2425-2431
采用小型密闭压力容器试验(MCPVT)装置,考察丁二烯的氧化特性,用碘量法测定氧化过程的过氧化值,探讨丁二烯的初期可能氧化反应生成,用顶空(进样)-气相色谱-质谱联用(HS-GC-MS)技术测定反应产物。结果表明,在氮气氛围中,即使到达105℃也未检测到丁二烯发生反应,在氧气氛围中,45℃下能测定过氧化物生成,65℃反应26 h,过氧化值达到9.1 mmol/kg。在70~100℃下,MCPVT能观察到显著的化学反应产生,压力减少。丁二烯在氧气中的反应是复杂的,主要产物有丙烯醛、呋喃、2,5二氢呋喃、2,3二氢呋喃、反式1,2-二乙烯基环丁烷、4-乙烯基环己烯、1,5-环辛二烯等。 相似文献
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Under high temperature and pressure, a continuous tubular reactor was successfully utilized to investigate the kinetics of 5-vinyl-2-norbornene (VNB) production. The process involved multiple cycloaddition reactions between cyclopentadiene (CPD) and 1,3-butadiene (BD). The results, spanning a wide range of operating conditions, indicate that higher temperature (180°C) and proper residence time (72 min) were conducive to efficient synthesis of VNB. The apparent kinetic parameters, including activation energies and pre-exponential factors, were acquired by fitting experimental data under integral operating conditions. The kinetic model was proven effective from a practical point of view in predicting the concentration changes of each product in the range 140 to 180°C and 30 to 80 wt.% concentration. This work provides a solid basis for the optimization of the VNB synthesis process. 相似文献
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H. A. Gueniche P. A. Glaude R. Fournet F. Battin-Leclerc 《Combustion, Explosion, and Shock Waves》2006,42(6):702-707
The structure of a laminar rich premixed 1,3-butadiene/CH4/O2/Ar flame has been investigated, 1,3-butadiene, methane, oxygen, and argon mole fractions being 0.033, 0.2073, 0.3315, and
0.4280, respectively, for an equivalence ratio of 1.80. The flame has been stabilized on a burner at a pressure of 6.7 kPa.
The concentration profiles of stable species have been measured by gas chromatography after sampling with a quartz probe.
The quantified species include carbon monoxide and dioxide, methane, oxygen, hydrogen, ethane, ethylene, acetylene, propyne,
allene, propene, cyclopropane, 1,3-butadiene, butenes, 1-butyne, vinylacetylene, diacetylene, C5 compounds, benzene, and toluene. The temperature distribution in the flame has also been measured.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 89–95, November–December, 2006. 相似文献
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The hydrogenation of 1,3-butadiene was successfully demonstrated using a microfabricated catalyst. The reaction was carried out at atmospheric pressure and 100°C with a hydrogen to hydrocarbon ratio of 125. Data from a thin film Pd/silica catalyst is also presented for comparison. The conversion for the microfabricated catalyst is more stable and slightly lower than that for the thin film catalyst; however, the geometric surface area of the thin film catalyst is 7.5 times greater than that of the microfabricated catalyst. The selectivity of the reaction products is greatly different between the two catalysts. The microfabricated catalyst has a much lower selectivity for 1-butene and favors the 2-butenes more so than does the thin film catalyst. 相似文献
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MgCl2-supported CoBr2 catalysts were prepared from mixture of MgCl2 and CoBr2L2 (L = triphenylphosphine or pyridine) in toluene. Polymerization of 1,3-butadiene was conducted over the catalysts combined with ordinary alkylaluminums as cocatalyst. The CoBr2(PPh3)2/MgCl2 catalyst gave polybutadiene with approximately 80% of 1,2 units, whereas cis-1,4-poly-butadiene was obtained with the CoBr2(C5H5N)2/MgCl2 catalyst. Addition of triphenylphospine to the latter catalyst caused a marked increase in the content of 1,2 units. The content of 1,2 units could be thus controlled in the range from 0 to 80% by changing the amount of triphenylphosphine. On the other hand, the CoBr2(PPh3)2/MgCl2 catalyst with very low content of CoBr2(PPh3)2 hardly displayed any activity. Addition of dimethoxydiphenylsilane to the catalyst gave polybutadiene containing 90 % of 1,2 units with a fairly high activity. 相似文献
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The selectivity and reactivity in the hydrogenation of 1,3-butadiene catalyzed by Tl-modified 5 wt% Pd/Al2O3 catalysts vary with amounts of Tl loading and with the reduction temperatures, that is, the main product was 1-butene and trans-2-butene for values of Tl loading of 0.5 and 2 in Tl/Pd atomic ratio, respectively, when the catalysts were reduced at 673 K. 1,3-butadiene was hydrogenated selectively towards 1-butene and trans-2-butene when the Tl modified 5 wt% Pd/Al2O3 catalyst of Tl/Pd = 2 was reduced at 300 and 373 K or above, respectively. On the catalyst with Tl/Pd = 2 reduced at 373 K or above, the butenes formed are not hydrogenated to butane, even after a long reaction time. These results suggest the formation of Pd-Tl alloy or intermetallic compounds during the reduction procedure which is responsible for the selectivity controlling in the reaction. TPR and XRD results were in consistence with the reaction data. 相似文献
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Won-Li Chiang Henry Chi-Chen Hsieh Raymond Chien-Chao Tsiang 《Journal of Polymer Research》1998,5(4):227-232
Poly(2,3-Dimethyl-1,3-butadiene) (PDMB) with varying contents of 1,4-and 1,2-structures has been anionically synthesized using
either n-butyllithium or sec-butyllithium as an initiator. The addition of tetrahydrofuran could enhance the rate of synthesis and effect the microstructure.
The Tm was higher for PDMB with a lower content of 1,2-structure, and the Tg was lower. This PDMB was then hydrogenated with a nickelocene/n-butyllithium catalyst system leading to the formation of HPDMB. The trans 1,4-structure unit was more difficult to hydrogenate due to its steric hindrance. Repetitive hydrogenation was necessary
in order to achieve a high degree of hydrogenation. The hydrogenated PDMB is an amorphous elastomeric material. The Tg’s were found to decrease with an increase in the degree of hydrogenation, concurrent with a gradual disappearance of the
Tm’s. Since a HPDMS with a low content of 1,2-structure resembles a head-to-head polypropylene, our data suggest that the Tg of an atactic head-to-head polypropylene lie between −30 and −35 °C. 相似文献
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The catalytic activity of Pd aggregates vapor-deposited on graphite has been measured in the 1,3-butadiene hydrogenation. It is generally decreasing with particle size. But, such a decrease is largely depending upon the hydrogen and the hydrocarbon pressure. Indeed, with low hydrocarbon pressure (about 1 Torr) and in presence of large excess of hydrogen (P
h
2/P
c
4
h
6=100) the activity of the smaller aggregates is comparable to that of larger particles. The different behaviour is consequently attributed to a size dependent deactivation. Such a deactivation could be due to carbon deposits generated by dehydrogenation of the diene admolecules. This behaviour is tentatively related with marked differences observed by XPS on the smaller aggregates, both with respect to the core level energies and to the density of states into the valence band. 相似文献
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The oxidation reaction kinetics of bitumen from Athabasca oil sands have been investigated in a flow-through fixed bed reactor using gas mixtures of various compositions. The system was modelled as an isothermal integral plug-flow reactor. The oxidation of bitumen was found to be first order with respect to oxygen concentration. Two models were examined to describe the kinetics of bitumen oxidation. In the first, the Athabasca bitumen is considered to be a single reactant and the oxidation reaction a single irreversible reaction. The activation energy for the overall reaction was found to be 80 kJ mol?1. This model is limited to calculating the overall conversion of oxygen. Because the fraction of oxygen reacting to form carbon monoxide and carbon dioxide increases with temperature, a more sophisticated model was proposed to take this into account. The second model assumes that the bitumen is a single reactant and that the oxidation of bitumen may be described by two simultaneous, parallel reactions, one producing oxygenated hydrocarbons and water, the other producing CO and CO2. The activation energy for the first reaction was found to be 67 kJ mol?1, and for the second, 145 kJ mol?1. This more sophisticated model explains the result that at higher temperatures more oxygen is consumed in the oxidation of carbon, because this reaction has a higher activation energy than the reaction leading to the production of oxygenated hydrocarbons and water. This model can also predict the composition of the product gases at various reaction conditions. 相似文献