新型惰性膜反应器中丁烷氧化脱氢制丁二烯和丁烯

The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes and operation conditions were investigated. The selectivity of C4 dehydrogenation products (bntene and bntadiene) was found to be higher in IMR than in FBR. The feeding mode with 20% of air mixing with butane in MIMR was found to be more efficient than the feeding mode with all air permeating through ceramic membrane. The MIMR gave the most smooth temperature profile along the bed.     

烃类晶格氧选择氧化制顺酐的强制周期操作反应技术

综述了烃类选择氧化制顺酐的生产工艺、反应技术。重点介绍了人为非定态催化反应技术的特点及在烃类晶格氧选择氧化反应中的应用 ,并对烃类选择氧化制顺酐反应提出了今后研究的方向。     

Carbon dioxide reforming of methane under periodic operation

The carbon dioxide reforming of methane under periodic operation over a commercial Ni/SiO₂·MgO catalyst was investigated at two different temperatures, 923 and 1,023 K. According to this operation, pure methane and carbon dioxide were alternately fed to the catalyst bed where methane cracking and the reverse Boudouard reaction took place, respectively. Therefore, hydrogen and carbon monoxide products appeared separately in different product streams. The performance of this operation was compared to that of the steady state operation with simultaneous feed of both carbon dioxide and methane. At 1,023 K, the methane conversion and hydrogen yield from the periodic operation initially decreased with time on stream and eventually leveled off at values about half of those obtained in the steady state operation with co-feed of both reactants. The decreased catalytic activity was due to the accumulation of carbonaceous deposit and loss of metal active sites. However, a different trend was observed at 923 K. The methane conversion and hydrogen yield were almost constant over the time on stream, although more carbonaceous deposit was progressively accumulated on the catalyst bed during the reaction course. At this temperature, the periodic operation offered the equivalent hydrogen yield to the steady state operation. The observed behavior could be due to the different mechanisms of carbon formation over the catalyst. Finally, it was found that cycle period and cycle split did not influence the reaction performance within the ranges of this study.     

Anaerobic catalytic oxidation of hydrocarbons in moving heat waves. Case simulation: Propane oxidative dehydrogenation in a packed adiabatic V-Ti oxide catalyst bed

The model simulation study has shown that the anaerobic process of oxidative dehydrogenation of propane under periodic alteration of feeding between propane and air may be realized in adiabatic catalyst beds in a stable continuous cyclic mode in a two-reactor scheme. In the case of an appropriate choice of process parameters (cycle duration and feeding flow rates) the process appears to be autothermal, i.e. it does not require any inlet gas preheating for stable operation. Compared with a similar steady-state adiabatic process, the proposed process is characterized with much lower maximum catalyst temperatures, giving the way to process pure propane without diluting it with inert gases, thus simplifying the downstream procedure of product separation. Predicted propylene yield is competitive with the one for the steady-state adiabatic process, while sufficient technological benefits of the new technology are expected (decrease in energy consumption and minimization of heat-exchange environment, process safety improvement, suppression of coke formation and efficient coke incineration).     

Fischer-Tropsch synthesis: supercritical conversion using a Co/Al2O3 catalyst in a fixed bed reactor

Modeling of the supercritical fluid mixture indicated that an important increase in density occurs above a threshold of approximately 4 MPa for the reaction temperature of 220 °C studied. While transport parameters of the fluid are largely retained, the observed improvement in wax solubility was noteable.A cobalt catalyst (25%Co/γ-Al₂O₃) was used in a fixed bed reactor under a pressure/density tuned supercritical fluid mixture of n-pentane/n-hexane. By using inert gas as a balancing gas to maintain a constant pressure, the density of the supercritical fluid could be tuned near the supercritical point while maintaining constant space velocity within the reactor. The benefits of the mixture allowed for optimization of transport and solubility properties at an optimum reaction temperature for Fischer-Tropsch synthesis with a cobalt catalyst. Indeed, above 4 MPa, increases in wax yields from sampling and carefully controlled gas measurements using an internal standard demonstrated an important increase in conversion due to greater accessibility to active sites after extraction of heavy wax from the catalyst. Additional benefits included decreased methane and carbon dioxide selectivities. Decreased paraffin/(olefin+paraffin) selectivities with increasing carbon number were also observed, in line with extraction of the hydrocarbon from the pore. Faster diffusion rates of wax products resulted in lower residence times in the catalyst pores, and therefore, decreased probability for readsorption and reaction to the hydrogenated product. Even so, there was not an observable increase in the alpha value for higher carbon number products over that obtained with just the inert gas.     

强制浓度周期振荡对丙烯部分氧化反应的影响

研究了强制浓度周期振荡对丙烯在 Mo-Co-Bi 氧化物催化剂上部分氧化制丙烯醛的影响。实验考察了在不同强制振荡周期与振幅下的丙烯转化率和丙烯醛选择性及收率的变化,并与稳态反应条件下的结果作了比较。发现丙烯浓度的各种脉冲方式及氧浓度的微量脉冲方式均可改善反应性能,但氧浓度的全脉冲方式效果不佳。对强制周期操作效应的机理作了探讨。     

Methanol Decomposition Over Copper/Silica: Effect of Temperature and Co-reactant on Carbon Deposition

The interaction of methanol with a copper/silica catalyst at 373 and 523K under reducing, oxidising and inert carrier gas flows has been studied. Under all conditions there is retained material associated solely with the copper. In general the retained species is adsorbed methanol/methoxy; only over an oxidised catalyst after treatment at 523K is there no evidence for adsorbed methanol/methoxy. Desorption of carbon dioxide is associated with an up-take in dioxygen indicating oxidation of a surface species, probably formate. After laydown under reducing or inert gas flow, the copper does not re-oxidise under the TPO gas flow, even at temperatures >673K indicating that material is still retained by the copper. Bulk re-oxidation of the reduced catalyst in the absence of retained species is rapid at 293K. Under oxidising conditions at 523K there is no evidence for adsorbed methanol/methoxy on the surface of the copper; in this case the retained species may be more akin to a carbonate.     

4-(2',4'-二氟苯基)-苯乙酮的拜耳-维利格反应研究

研究了题示化合物的拜耳－ 维利格反应特性,考察了温度、催化剂、惰性气体保护、操作方式、过酸用量等影响因素。确定了该反应的最佳条件为：５０ ℃,复合催化剂催化,惰性气体保护,两步法操作,ｎ（过酸）∶ｎ（酮）＝ ３∶１。揭示了有无惰性气体保护对该反应的反应速率和收率有重要的影响这一特性,并给出了解释。在最佳条件下,整个反应时间只需７ ｈ,且收率能达到９２ ％ 。     

膜控制氧化反应器中丁烯氧化脱氢的研究

在气体均布的无机膜控制氧化反应器上进行了丁烯氧化脱氢制丁二烯反应,并将其与固定床方式反应的实验结果进行了对比,结果表明在实验范围内膜反应器比传统的固定床反应更为有效。建立了描述控制氧化膜反应器操作性能的数学模型,并将模型求解值与实验值对比,吻合良好。     

胜利褐煤负载镍生物质气化催化剂实验研究

为获得较低温度下生物质焦油高效裂解气化的廉价型催化剂,基于褐煤富含含氧官能团特点,通过离子交换法将镍负载到胜利褐煤上制备褐煤负载镍催化剂(Ni/SLC)。研究了溶液p H值和炭化温度对催化剂物理化学性质的影响,得到Ni/SLC催化剂最佳制备条件,最后在两段式移动床石英反应器中将催化剂用于玉米芯挥发分的催化气化,研究了催化剂对生成气产量和碳平衡的影响。结果表明:p H值为11,炭化温度为650℃时制备的Ni/SLC比表面积最大达到266.3 m2/g,镍微晶尺寸较小为5.0 nm。催化气化实验表明:650℃下Ni/SLC催化剂具有高的焦油裂解活性,气体产量高达43.9 mmol/g,相当于无催化实验气体总产量的3.3倍;水蒸气气化可将热解焦油完全气化,气体产量为85.1 mmol/g,H2产量高达61.9 mmol/g,占气体总量的72.7%,说明Ni/SLC催化剂可作为生物质催化气化制氢的潜在催化剂。     

Mass transfer effects in the H2SO4 catalyzed pivalic acid synthesis

The synthesis of carboxylic acids from alkenes, carbon monoxide and water according to the Koch process is usually carried out in a stirred gas–liquid–liquid multiphase reactor. Due to the complex reaction system with fast, equilibrium reactions and fast, irreversible reactions the yield and product distribution depend on a number of process parameters. The effect of some of these parameters was studied for the production of pivalic acid, using sulfuric acid as a catalyst. For the 96 wt.% sulfuric acid catalyst solution used the main reactions are relatively fast with respect to mass transfer and mixing. Therefore, aspects like the position of the injection point, inlet concentration, agitation intensity and injection rate all influence the yield obtained. The presence of an inert organic liquid phase was found to be beneficial, due to a combined effect of enhanced gas–liquid mass transfer and a ‘local supply’ effect for carbon monoxide near the hydrocarbon reactant inlet.     

Heterogeneously catalyzed oxidative dehydrogenation of isobutyric acid to methacrylic acid: A new application of periodic flow reversal

The heterogeneously catalyzed oxidative dehydrogenation of isobutyric acid in a fixed bed reactor using molybdenum (Mo) heteropoly acids as catalysts shows a loss of Mo into the gas phase due to the formation of volatile Mo-complexes under reaction conditions. To avoid this loss of catalyst and to keep the catalytic material in the fixed bed and thus increase the catalyst's lifetime, the process has been performed under periodic flow reversal within the reactor. In this work, periodic flow reversal is tried in a semi-pilot test reactor as a method to fix the Mo-compounds in the catalyst bed. The influence of this mode of operation on the temperature profile in the reactor, on conversion, selectivity and yield of the product methacrylic acid is investigated in comparison with the process without periodic flow reversal.     

MoVTeNbO_x催化剂焙烧条件对丙烷氧化制丙烯酸的影响

制备了Mo1V0.25Te0.13Nb0.12Ox催化剂,研究了焙烧条件（焙烧方式、焙烧气氛和焙烧温度）对该催化剂在丙烷选择氧化制丙烯酸反应中的影响。结果表明,两段间歇式焙烧要优于一段式连续焙烧所得催化剂的催化效果,适宜的预焙烧温度既有利于脱除挥发性物质和化学结合水,又能避免活性组分氧化生成不利的晶相;在惰性气氛中焙烧所得催化剂的催化效果要优于在弱氧化性气氛中焙烧,丙烷转化率和丙烯酸收率随着焙烧温度的升高先增加后减小,在600 ℃时达到最大值。     

Steady and unsteady co oxidation on platinum with allowance for external diffusion retardation

A mathematical model for catalytic oxidation of CO on a spherical platinum catalyst with allowance for the influence of gas diffusion is developed and studied. The model explains the origin of the effects of bifurcation and oscillation of a steady reaction rate. The model is based on the four-stage catalytic Elley-Ridley mechanism. In contrast to the case where gas diffusion retardation is ignored and only one basic form of catalyst phase plane exists, owing to the consideration of the effect of gas diffusion, we found two additional regimes of catalyst operation. These additional regimes make it possible to explain the origin of the effects of bifurcation and oscillation of the steady reaction rate by which the reaction rate for a steady-state surface is meant. When the surface concentrations of adsorbing reagents or free catalytic sites vary in the course of the reaction, the regime of catalyst operation is called unsteady. The reaction rate when the catalyst reaches a steady state is determined for all possible regimes of catalyst operation. Based on analysis of the results obtained, we give some practical recommendations on an increase in the reaction rate. The hysteresis of the reaction rate is explained.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 6, pp. 52–61, November–December, 1996.     

混合碳四全加氢催化剂第一次再生过程分析

混合碳四来自丁二烯抽提装置和MTBE装置生产的含炔碳四、炼厂轻烃回收装置生产的重碳四,该部分碳四经过全加氢饱和其中的烯烃和炔烃后可作为裂解原料。混合碳四中烯烃含量(摩尔分数)较高,通常占65%以上。随着装置运行,烯烃在反应器中聚合、结焦,长时间累积会堵塞催化剂孔道,造成催化剂活性下降,床层压差升高,影响产品质量和装置运行,需要停车再生催化剂。分析了再生过程,评价了再生结果,为装置后续运行提供了理论基础。     

Heat transfer effect of inert gas on multi-tubular reactor for partial oxidation reaction

The heat transfer effect of an inert gas on a multi-tubular reactor for a partial oxidation reaction has been determined. The model reaction system in the study was partial oxidation of propylene to acrolein. Both theoretical modeling and experimental studies have been performed to determine the heat transfer effect of inert gas on the system. Among many inert gases, CO₂ was selected and tested as a diluent gas for the partial oxidation of propylene to acrolein system instead of conventionally used N₂. The productivity increase through changing the inert gas from N₂ to CO₂ was possible due to the heat transfer capability of CO₂. In this study, by replacing the inert gas from N₂ to CO₂, productivity increased up to 14%.     

周期性输入组分和扫气在改善钯膜反应器甲烷部分氧化制氢中的作用(英文)

The partial oxidation of methane under periodic operation over Ni/γ-Al2O3 catalyst was investigated in a Pd-membrane reactor.The effects of key parameters such as the inlet composition and the sweeping gas on methane conversion and the hydrogen recovery are numerically established with two periodic input functions.In order to analyze the effect of the inputs modulation,the reaction was performed under low steam to methane ratio at a moderate temperature and pressure.It was obtained that to achieve process intensification is to operate the process in a periodic way.The main results show that the periodic input functions can improve the performance of the process compared to the optimal steady state operation.Moreover,there is an optimum amplitude of manipulated inputs leads to a maximum of hydrogen recovery.It is noteworthy that the comparison between the predicted performance via the sinusoidal and the square ways show that the better average performance was obtained with the square way.     

Highly effective cobalt catalyst for wax production in Fischer-Tropsch synthesis

Fischer-Tropsch synthesis (FTS) was carried out in a fixed bed reactor with a highly effective cobalt catalyst for wax production. The procedure for reducing the inactive cobalt oxide to the active cobalt catalyst was examined by X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The results showed that 300 ml/min H₂ at 350 °C for 16 h was suitable for reducing the inactive Co oxides to active metallic Co sites. In the case of the powder and pellet type cobalt catalysts with a reactant (H₂/CO = 2:1) flow rate of 15 g_cat min L⁻¹, catalyst deactivation occurred as a result of mass transfer limitations of the hydrocarbon and water produced on the catalyst. On the other hand, the pellet type cobalt catalyst with a reactant flow rate of 45 g_cat min L⁻¹ showed activity not only for liquid hydrocarbon (C₅₊) formation but also for gas product (CH₄ and CO₂) formation. In particular, the methane yield reached almost 20% due to heat transfer limitation in the catalyst. Considering the heat and mass transfer limitations in the cobalt catalyst, a Co-foam catalyst with an inner metallic foam frame and an outer cobalt catalyst was developed. SEM-EDS Co-mapping revealed the cobalt atoms to be distributed equally over the surface of the Co-foam catalyst. The Co-foam catalyst was highly selective toward liquid hydrocarbon production and the liquid hydrocarbon productivity at 203 °C was 52.5 ml  h⁻¹, which was higher than that by the Co-pellet. In addition, the chain length probability, α, by the Co-foam catalyst was 0.923 and wax formation was especially favored.     

Oxidation of butenes to maleic anhydride on MnMoO4 based catalyst

The oxidation of n-butene-1 was carried out in a stirred tank reactor and in a pulse reactor using MnMoO₄ as a catalyst. This catalyst exhibits a fairly good selectivity to maleic anhydride. MnMoO₄ shows a polyfunctional nature; it is possible to distinguish the properties of isomerization, dehydrogenation, oxidation with oxygen insertion, and complete oxidation by varying parameters such as temperature, oxygen concentration and contact time.The compositions of the products in the oxidation of n-butene-1 carried out in a pulse reactor are completely different in the presence and in the absence of oxygen, respectively. In the absence of oxygen, MnMoO₄ is a very selective catalyst in the dehydrogenation of n-butene-1 to butadiene. In the presence of oxygen, CO and CO₂ are the main products together with small amounts of maleic anhydride.The selectivity of MnMoO₄ to butadiene formation has been attributed to the presence of MoO bonds which are responsible for dehydrogenation reactions.A monocenter oxidation mechanism, accounting for the formation of CO, CO₂, and maleic anhydride, has been proposed in which the gaseous oxygen is considered to be adsorbed on the same center of the hydrocarbon.     

Complex metal-oxide catalysts for selective oxidation of propane and derivatives: I. Catalysts preparation and application in propane selective oxidation to acrylic acid

Several parameters involved in preparing the complex metal-oxide (CMO) catalysts (M_aV_bTe_cNb_dO_n, M: Mo and W) for the selective oxidation of propane to acrylic acid (AA) were investigated and discussed. These include the role each metal element plays and the effects on the performance of the catalysts exerted by the proper metal ratio, as well as various preparation methods, such as the mixing of starting chemicals to form an aqueous precursor mixture, the solvent removal, and the proper calcination atmosphere and gas flow. It was found that each metal element plays a critical role and while an appropriate MoVTeNb metal ratio is critical to the formation of an effective catalyst, each and every step of the preparation methods also have profound effects on the structures and performance of the resulting catalysts. The preferred preparation method for an effective MoVTeNb oxide catalyst includes the intimate mixing of all starting chemicals to form a precursor solution, drying via rotavap for solvent removal followed by calcination under a non-flow inert atmosphere. Using this preferred preparation method, effective complex metal-oxide catalysts can be prepared which affords up to 73% propane conversion and 42% one-pass yield to acrylic acid, while undesirable preparation methods, in contrast, lead to very ineffective catalysts of the identical composition.