共查询到20条相似文献,搜索用时 78 毫秒
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Fe-Mn催化剂的费托合成产物分布动力学 总被引:1,自引:0,他引:1
在固定床反应器上进行了Fe-Mn超细粒子催化剂F -T合成反应动力学研究。以碳化物机理为基础推导出简化的F -T合成产物生成动力学模型 : RCnH2n 2 =kHC5PH2 (1-α)αn在温度 5 76~ 6 10K ,压力 1 5~ 2 5MPa ,空速 2 5 0 0~ 45 0 0h-1和原料气H2 /CO比为 2 0的条件下进行动力学试验 ,通过模型拟合 ,求得动力学方程参数 : kHC5=kHC5(5 80K)exp[EaR(1T - 15 80 ) ]其中 ,kHC5(5 80K) =2 82× 10 -6mol/ (mlcat·MPa·s) ,Ea=6 6 0 7kJ/mol结果表明 ,该模型与实验值拟合较好 ,链增长几率α与温度和反应器内H2 /CO比具有简单的关系 :α =1/ (1 ρRHC)。 相似文献
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以共沉淀法所制的工业铁硅球体催化剂(indus-FS)为原料,用改进的有机胺蒸气相传输转化法,得到了负载高分散铁的交织氧化硅纳米线球体催化剂(NW-FS),并用于费托合成反应.在所制纳米线催化剂中,原料催化剂中氧化硅在氧化铁诱导下成功地转变成纳米线交织微球载体,而氧化铁组分则高度分散在氧化硅纳米线上.用扫描电镜、透射电镜、X射线衍射、低温氮吸附、X射线光电子能谱和程序升温还原等方法对所得纳米线催化剂进行了表征.在费托合成中,纳米线铁硅催化剂由于其特殊的堆积结构所导致的低的扩散阻力和高的铁活性组分分散度,提高了低碳烯烃尤其是乙烯的选择性.纳米线铁硅催化剂上低碳产物(C2–C4)的烯烷比为3.3,高于母体工业催化剂的1.9. 相似文献
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沉淀铁费托合成催化剂焙烧工艺的优化研究 《燃料化学学报》2017,45(2):235-242
通过DOE实验设计对沉淀铁费托合成催化剂焙烧过程进行了优化,并给出了焙烧过程的分子模拟与粒子长大模型。结果表明,随着焙烧温度的升高和焙烧时间的延长,催化剂的孔容减小,堆比及骨架密度增加,耐磨性改善。BET表面与磨耗的变化趋势一致,即比表面积越小磨耗越小;磨耗与密度成线性反比关系,密度越高磨耗越小。通过焙烧工艺的优化,可调变Cu、Si通过O原子与Fe原子的键合作用及催化剂的粒子粒径,得到较高F-T活性且稳定性好的沉淀铁催化剂。在该实验中,优化的焙烧温度为560℃。 相似文献
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利用高通量技术设计并运行了16路平行动力学固定床反应器,用于测量不同接触时间下的稳态反应物消耗速率和产物生成速率,研究了钴基费托催化剂的宏观动力学,包括C1~C4烷烃与烯烃的稳态反应速率及其随床层的分布,以及它们与反应器温度的关系.在等温固定床非扩散限制的反应条件下,除C1和C2烃类外,Cn的生成速率及CO/H2的消耗速率均随接触时间的增加先上升后下降,且烯烃生成速率的最高点较烷烃更靠近反应器入口;反应温度对速率的影响与转化率有关:生成烷烃的表观活化能大于烯烃.高通量动力学反应器可用于生成宏观动力学数据库,以预测催化剂在工业固定床反应器中的行为. 相似文献
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以骨架Co 为内核, 通过水热合成在其表面包覆HZSM-5 分子筛膜, 制备了具有核壳结构的骨架Co@HZSM-5 催化剂. 采用元素分析、氮物理吸附、粉末X射线衍射、扫描电子显微镜、氨脱附等手段对催化剂的物理化学性质进行了表征. 在气相费托合成反应中, 骨架Co@HZSM-5 核壳催化剂显示了比物理混合的骨架Co-HZSM-5催化剂更好的催化裂解作用, 故C5-C11汽油段产物选择性高. 通过改变水热时间, 对分子筛膜厚进行了调节, 发现适当的分子筛膜厚在保证催化剂具有较高活性的前提下, 使长链费托合成产物完全裂解, 高选择性地得到汽油段产物. 提高反应温度有利于费托合成反应的进行以及分子筛上裂解效率的提高, 但产物分布向短链烃方向移动. 在水热4天制备的骨架Co@HZSM-5核壳催化剂上及反应温度为250 ℃时, 得到了最佳反应结果, 汽油段产物选择性达79%, 说明费托合成活性中心与催化裂解酸中心之间形成了良好的协同作用. 相似文献
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森林可燃物热解动力学参数的优化计算是构建综合热解模型的关键步骤。传统的基于梯度的优化方法收敛速度快但全局寻优能力不足,基于“生物进化理论”的遗传算法具有全局寻优能力但收敛速度慢。本研究首先探讨了单纯的遗传算法对初始值设置的依赖,发现设定合适的初始值能够稳定计算结果,加快算法的收敛速度。针对初始值未知的情况,本文提出了将单纯的遗传算法与迭代算法相结合构建混合型遗传算法的流程。然后以樟子松松枝为例,采用热重分析仪开展了森林可燃物热解实验。假设可燃物热解失重过程遵循三步一级平行反应模型,通过对比单纯遗传算法和混合型遗传算法的收敛过程,发现混合型遗传算法能够快速地获取全局最优的动力学参数,显著地提高遗传算法的优化性能。 相似文献
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溶液间歇结晶动力学模型的新型算法 总被引:2,自引:0,他引:2
针对溶液间歇结晶过程, 基于粒数衡算理论和ΔL定律, 借助分段归纳的研究方法, 建立了晶体粒度分布函数各阶矩量的关联式. 利用此关联式, 对文献模型中晶体粒度分布函数的二阶矩量进行替换, 并结合计算机程序设计, 可直接拟合得到结晶体系的成核和生长动力学参数, 从而为结晶动力学模型的求解建立了一种新型算法. 通过对文献报道的硝酸钾水溶液和混二甲苯溶液两组结晶数据的模拟计算, 结果发现, 运用该算法求取的结晶成核和生长动力学参数均与传统的矩量变换法的计算结果相近, 但新建算法无需预知结晶体系的总传热系数. 相似文献
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A new technique, called modulated thermogravimetry, is introduced as a tool for obtaining continuous kinetic information for
decomposition and volatilization reactions. The approach makes use of an oscillatory temperature program to obtain kinetic
parameters during a mass loss. MTGA™ may be used under quasi-isothermal conditions to observe a single mass loss or may be
combined with linear heating rate or Hi-Res™ controlled rate thermogravimetry to scan from one mass loss region to another.
Results obtained are in agreement with those obtained by other kinetic methods.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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V. J. Fernandes Jr. A. S. Araujo G. J. T. Fernandes J. R. Matos M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2001,64(2):585-589
High density poly(ethylene) has been submitted to thermal degradation alone, and in the presence of silicoaluminophosphate
SAPO-37. The processes were carried out in a reactor connected on line to a gas chromatograph/mass spectrometer in order to
analyze the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature until 800°C,
under nitrogen dynamic atmosphere, with multiple heating rates. From TG curves, the activation energy related to degradation
process was calculated using the Flynn and Wall multiple heating rate kinetic model for pure polymer (PE) and for polymer
in the presence of catalyst (PE/S37). SAPO-37 showed good selectivity for low molecular mass hydrocarbons in PE catalytic
degradation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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In this work, kinetic data of crystallization processes have been determined by measurement of the intensities of reflection of X-ray diffraction spectra and modeled using the Avrami-Eroféev and Jander expressions. We have created a simple Microsoft Excel spreadsheet that allows students to calculate the kinetic data. Students will be able to calculate the kinetic parameters of any crystallization process, for example, hydrothermal crystallization of catalytic materials like zeolites. The possibility of using the spreadsheet with different models or expressions and discriminating among them is also validated by comparing the model results with experimental data (differential thermal analyses, DTA) from papers available in the recent literature. 相似文献
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Experimental data (the rate constants and activation energies) for seven reactions of direct substitution of one atom for another D + CH3R CH2DR + H, D + NH3 DNH2 + H, D + H2O HOD + H, F + CH3X CH3F + X (X = F, Cl, Br, and I) involving atoms D and F and molecules C2H6, H2O, NH3, CH3F, CH3Cl, CH3Br, and CH3I are analyzed using the parabolic model of a bimolecular radical reaction. The activation energies for the thermally neutral analogs of these substitution reactions are calculated. Atomic substitution involving deuterium atoms has a lower activation energy of a thermally neutral reaction than radical abstraction or substitution. 相似文献
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用热动力学方法对高分子固化反应动力学进行研究,在RD-Ⅰ型热导式自动量热计的基础上,设计了反应器,测定了端羟基聚丁二烯(HTPB)与甲苯二异氰酸酯(TDI)固化反应的动力学参数(表观活化能和反应速率常数),结果与文献值、粘度法和红外光谱法的结果相符。 相似文献
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Natural resveratrol is widely used in medicine, food, and cosmetic because of its pharmacological properties. Due to its low
content in plants, this study was conducted to increase the yield of resveratrol by microorganism transformation. Fungi Aspergillus niger AN-2436 was employed in biotransformation to produce resveratrol from polydatin, and genetic algorithm (GA) was used to optimize
the fermentation conditions. A transformation ratio of higher than 95% was achieved in the following conditions: culture temperature
of 30.3 °C, inoculum size of 20% (v/v), rotating speed of 147 rpm, and cultivation time of 36 h. Compared with the polydatin absorbance under the experimental
conditions obtained by single-factor, orthogonal experiments and average absorbance, the GA provides the optimum experimental
conditions, under which the largest transformation rate was achieved. The final transformation product obtained was identified
as resveratrol, and it was proved by high-performance liquid chromatography, infrared, mass spectrometry, and nuclear magnetic
resonance. 相似文献
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用巨正则系综Monte Carlo方法(GCMC)来模拟ZrO2柱撑粘土对天然气主要成分甲烷的吸附. 为了更好地反映甲烷与层柱粘土无机层板的相互作用, 对墙势模型中的尺寸参数σfw和能量参数εfw取值进行了优化. 我们系统地改变甲烷在蒙脱土晶体结构中的位置, 建立起一系列甲烷与层板相互作用的Lennard-Jones势能曲线, 通过最小二乘法拟合这些Lennard-Jones势能曲线得到一系列的σfw和εfw值, 利用拟合得到的σfw和εfw算术平均值作为墙势模型中两个交互作用参数的取值进行分子模拟, 模拟结果与文献实验值符合较好. 在此基础上, 进一步模拟了3种不同孔率, 层间距为0.64 nm的ZrO2柱撑粘土(ZPC)在245 K下对临界态甲烷的吸附, 发现 3~4 MPa是ZPC材料吸附甲烷较适合的压力范围, 而且孔率大的ZPC有利于甲烷的吸附. 相似文献