Co-CeO2/SiO2催化剂上的费-托反应性能

 考察了反应条件对Co－CeO2／SiO2催化剂上费－托合成反应性能的影响，并对催化剂进行了1000h稳定性和再生性能实验．结果表明，添加铈助剂后，催化剂具有良好的稳定性和再生性能，整个过程中CO转化率为89．7％，C5＋烃类（主要组成为C10～C20直链烃）选择性为81．0％，链增长几率为0．90．催化剂的活性表面被反应产物蜡覆盖时，阻碍了反应物与活性中心的结合，是导致催化剂活性降低的主要原因．     

助剂CeO2对Co/Al2O3催化剂上F-T合成反应性能的影响

 在用于F－T合成的Co／Al2O3催化剂中加入少量助剂,能够提高CO转化率和C5＋烃选择性．主要考察了助剂CeO2添加量和催化剂焙烧温度等因素对F－T合成反应的影响,并通过程序升温还原、程序升温氧化及X射线衍射等手段对催化剂进行了表征．结果表明,在Co／Al2O3催化剂中加入少量CeO2（n（Ce）／n（Co）＝0．1～0．14）,能够有效提高催化剂的催化活性和C5＋烃选择性;焙烧温度则以相反的趋势控制F－T反应活性和链增长几率;助剂的加入降低了催化剂的起始还原温度,改善了催化剂的还原性能．但是,催化剂的积碳量有所增加,经10h反应后,催化剂上存在两种类型的积碳．     

钴基F-T合成重质烃催化剂载体效应的研究

 考察了ZrO2,Al2O3和SiO2等载体对Co基催化剂上CO加氢反应性能的影响．结果表明,载体的特性明显影响CO转化率、产物分布及链增长几率．氧化态催化剂上的钴主要以Co3O4形态存在,其晶粒大小的顺序为Co／ZrO2＜Co／SiO2＜Co／Al2O3．XPS测试结果表明,载体与钴之间存在着相互作用．     

低碳醇合成Raney Cu—Co催化剂的研究：Ⅰ.反应性能考察

本文在５６３Ｋ、６ＭＰａ及Ｈ２／ＣＯ＝２的条件下，考察了Ｃｕ／Ｃｏ比不同的几个ＲａｎｅｙＣｕ－Ｃｏ催化剂的反应性能，结果表明：ＲａｎｅｙＣｕ－Ｃｏ催化剂上ＣＯ加氢产物主要为Ｃ１－Ｃ６正构醇及Ｃ１－Ｃ８正构烃。烃和醇产品的分布均符合Ｓｃｈｕｌｚ－Ｆｌｏｒｙ方程，但醇产品的链增长几率（０．３－０．５５）均小于烃产品的值（０．６－０．７５）。Ｃｕ／Ｃｏ比不同的催化剂在进入活性稳定区之前。均经过了一个不尽     

合成气制低碳烯烃用Fe／AC催化剂的制备及性能表征

 研究了以活性炭（AC）作为载体制备的铁基催化剂，通过对不同铁盐、活性炭和助剂的筛选，研制出对合成气转化为低碳烯烃具有高活性和高选择性的催化剂．对反应前及反应过程中催化剂体相结构的XRD测试结果表明，Fe－Cu－K／AC催化剂在反应前主要由α－Fe，Fe3O4和Cu0组成，经合成气反应后主要由α－Fe，Fe5C2，Fe7C3，Cu0和K2O组成．Fe－Mn－K／AC催化剂的晶体结构主要以Fe嵌入MnO中形成的（Fe，Mn）O结构存在．实验中得出的α－Fe，FexCy及（Fe，Mn）O与激光热解法制备的催化剂的的晶体结构相似．对催化剂的制备方法进行了筛选，考察了不同助剂Cu，Mn，Si和K等元素对催化剂性能的影响．结果表明，以草酸铁为铁源，椰壳炭为载体制备的Fe－Mn－K／AC催化剂的催化效果最佳，在空速600h－1，压力1．5MPa和温度320℃条件下，CO转化率可达97．4％，C＝2～C＝4选择性可达68．0％．     

低碳醇合成Raney Cu－Co催化剂的研究Ⅰ．反应性能考察

本文在５６３Ｋ、６ＭＰａ及Ｈ＿２／ＣＯ＝２的条件下，考察了Ｃｕ／Ｃｏ比不同的几个ＲａｎｅｙＣｕ－Ｃｏ催化剂的反应性能。结果表明：ＲａｎｅｙＣｕ－Ｃｏ催化剂上ＣＯ加氢产物主要为Ｃ＿１－Ｃ＿６正构醇及Ｃ＿１－Ｃ＿８正构烃。烃和醇产品的分布均符合Ｓｃｈｕｌｚ－Ｆｌｏｒｙ方程。但醇产品的链增长几率（０．３－０．５５）均小于烃产品的值（０．６－０．７５）。Ｃｕ／Ｃｏ比不同的催化剂在进入活性稳定区之前，均经过了一个不尽相同的活性波动区，活性趋于稳定所需时间随Ｃｕ／Ｃｏ比增大而缩短。Ｃｕ／Ｃｏ＝０．３－１．５（原子比）时，就醇收率而言，ＲａｎｅｙＣｕ－Ｃｏ催化剂明显高于共沉淀Ｃｕ－Ｃｏ催化剂，Ｃｕ／Ｃｏ＝０．８（原子比）时，稳定醇收率达０．５７ｇ·ｇ￣（－１）·ｈ￣（－１）。     

K改性β-Mo2C催化剂CO加氢合成低碳混合醇的研究

制备系列K改性的β-Mo2C催化剂并对其CO加氢合成低碳混合醇性能进行了考察。结果表明,K改性使β-Mo2C催化剂的CO加氢选择性发生显著变化。β-Mo2C催化剂CO加氢的产物主要为C1～C4烷烃,经K改性后β-Mo2C催化剂上产物主要为C1～C5低碳醇,其中高级醇(C2+OH)选择性可达到33.78%。通过对碱金属质量分数的考察发现,当K/Mo（原子比）为0.2时,总醇选择性达到最大值,低碳醇的时空收率达到0.12 g/（mL·h－１）。β-Mo2C催化剂上醇烃产物均符合线性Anderson-Schultz-Flory（A-S-F）分布曲线,而K改性β-Mo2C催化剂上醇产物为独特的甲醇负偏离A-S-F分布。可见,K助剂的加入有效促进了低碳醇的形成,尤其是促进了C1OH到C2OH的链增长步骤。     

Fe_2O_3／ZrO_2催化剂上一氧化碳加氢反应制低碳烯烃──I．催化剂反应性能及反应过程中铁物相的变化

用浸渍法制得一系列不同铁负载量的Ｆｅ２Ｏ３／ＺｒＯ２催化剂，应用催化反应评价结合穆斯堡尔谱对催化剂的ＣＯ加氢反应性能、催化剂活性相结构及催化剂铁物种在合成气反应过程中的物相变化进行了研究．结果表明，铁负载量的大小对于Ｆｅ２Ｏ３／ＺｒＯ２催化剂的Ｆ－Ｔ反应催化性能有很大影响，铁负载量适当时，Ｆｅ２Ｏ３／ＺｒＯ２催化剂铁锆间适当的强相互作用使得催化剂在保持较高催化活性的同时高选择性地生成低碳烯烃，产物分布偏离Ｓｃｈｕｌｚ－Ｆｌｏｒｙ分布规律．     

浆态反应器中铁／活性炭催化剂上还原研究

众所周知，费托合成（Fischer-Tropsch synthesis,FTS)反应是一个有理论与应用价值的研究课题。数十年来，学者们已发现了铁系，钴系和钌系等具有优良FTS反应性能的催化剂体系，铁／活性炭（Fe/Activated Carbon,AC)催化剂是中国科学院大连化学物理研究所八十年代末开发的一类费托合成催化剂，由于活性炭载体发达的孔结构使得该催化剂上FTS反应产物中汽油，柴油选择性高（烃类碳数小于20）和油收率大（C5^ ,112g/m^3 sysgaa)^[1,2]，具有工业放大前景。本文采用1L浆态床反应器，应用不同的还原方法（原位高压还原和反应器外还原）和XRD物相表征手段，了铁／活性炭催化剂在浆态床中的还原与反应问题，得到了一些有用的信息。     

Zr-Mn-K催化剂超临界相合成甲醇与异丁醇的研究

用共沉淀法和超临界流体干燥法,分别制备了Ｚｒ－Ｍｎ－Ｋ沉淀型催化剂和超细催化剂．以正十一～十三烷的混合物为超临界介质,在反应温度３６０～４１０℃、合成气压力７．５ＭＰａ、ＧＨＳＶ１７００ｈ－１及介质压力２．０８ＭＰａ的实验条件下,分别考察了超细催化剂和沉淀催化剂的气相和超临界相催化合成气制甲醇、异丁醇的性能．气相和超临界相反应的研究均表明,超细催化剂催化合成异丁醇的活性高于沉淀催化剂;在超临界条件下反应,超细催化剂上产物的异丁醇含量较高（为２３％～３２％）,甲醇含量为２２％～３３％,其它醇均在１０％左右．气相与超临界相反应结果的对比显示,超临界流体促进产物的脱附与传递,提高了ＣＯ的转化率．但超临界流体对甲烷的萃取作用强于对醇的萃取,醇选择性低于气相反应．在超临界条件下合成甲醇、异丁醇仍遵循异丁醇形成的链增长机理,超临界流体改变了链增长各步骤的相对速度,致使超临界相反应的产物分布不同于气相反应的产物分布．     

Alumina-supported iron catalyst - long-term study of the light product distribution in Fischer-Tropsch synthesis

Several models have been proposed to describe the carbon number product distribution and mechanism in Fischer-Tropsch synthesis (FTS). However, these models have not fully explained the product distribution and mechanism owing to the wide range and complexity of hydrocarbons in FTS. This study was conducted based on the Yao and Anderson-Schulz-Flory (ASF) carbon number product distribution models for light (C₁–C₆) hydrocarbon products of a Fe/Al₂O₃ catalyst. The product distribution based on the molar ratio of olefin to paraffin (O/P) and the neighboring olefins was also studied in order to better understand the mechanism in FTS and C₂ olefin deviation during FTS.Two sets of experiments (A and B) with different reaction conditions were conducted in microtubular fixed-bed reactors on the Fe/Al₂O₃ catalyst for 2249 h and 360 h, respectively. We found that the α values from the Yao and ASF carbon number product distribution models are relatively similar. The α values from the Yao carbon number product distribution plots are relatively constant, irrespective of the reaction conditions.Interestingly, it was also found that the secondary reactions of the C₂ olefin by re-adsorption to produce paraffins and long-chain olefins are dependent on the CO conversion and the reaction temperature during the FTS. Also, the product distribution of the neighboring olefins during the reduction condition gave a similar trend to what was observed for other reaction conditions. This result confirmed what was observed in the Yao and ASF carbon number product distribution of the olefins.     

An investigation of chain growth probability in Fischer-Tropsch synthesis over an industrial Fe?Cu?K catalyst

The chain growth probability of Fischer-Tropsch synthesis (FTS) was investigated on the basis of data from a set of experiments over an industrial coprecipitated Fe−Cu−K catalyst developed by the Institute of Coal Chemistry (China). The experimental results show that the ASF chain growth probability (α) depends on operation conditions, temperature (T) and H₂/CO ratio in the feed. α decreases with T or H₂/CO feed ratio increasing. The experimental results also show that chain growth probabilities of hydrocarbons are not constant, but a function of carbon number. This deviation from ASF assumption is further discussed.     

Product distributions of Fischer-Tropsch synthesis over Co/AC catalyst

The product distributions of Fischer-Tropsch synthesis over Co/AC catalyst are investigated under different reaction conditions in an integral fixed bed reactor.It is found that the product distributions deviate from the ASF distribution.The deviation from ASF distribution is analyzed by taking the readsorption of alkenes and the following secondary reaction into consideration.It is noted that the contents of alcohol,alkene and alkane decline with the increasing carbon number,showing a slighter declining tendency of alkanes than those of alkenes and alcohols.It is also found that high temperature,space velocity,H2/CO in feed gas and low pressure are preferential for light hydrocarbons and alcohols while against the chain propagation.The effect of space velocity on the product distributions especially on the light products is not obvious.It is noticed that low temperature,space velocity,H2/CO and high pressure lead to high contents of alcohols;high temperature,H2/CO and low space velocity lead to high contents of alkanes.The effect of pressure on the amounts of alkanes is not significant;high space velocity and low temperature,pressure,H2/CO are preferential for alkenes.     

Effect of nano-particle size on product distribution and kinetic parameters of Fe/Cu/La catalyst in Fischer-Tropsch synthesis

Effects of nano-particle size on hydrocarbon production rates and distributions for precipitated Fe/Cu/La catalysts in Fischer-Tropsch synthesis were investigated. Nano-structured iron catalyst was prepared by micro-emulsion method. The concept of two superimposed Anderson-Schulz-Flory (ASF) distributions has been applied for the representation of the effects of reaction conditions and nano-particles size on kinetics parameters and product distributions. These results reveal that by reducing the particle size of catalyst, the break in ASF distributions was decreased. Also useful different kinetics equations for synthesis of C_3 to C_9 and C_(10) to C_(22) were determined by using α_1 and α_2 chain growth probabilities.     

工业Fe-Mn催化剂上基于详细反应机理的F-T合成动力学模型Ⅱ.不同校正方法的动力学模型分析

 通过平衡闪蒸模拟催化剂孔道液体组成、烯烃物理吸附和虚拟烯烃分压等方法,考察了化学反应以外的非本征因素对F-T合成动力学模型的校正. 平衡闪蒸模拟催化剂孔道中烯烃组成的校正计算结果表明,在烯烃浓度出现峰值前,溶解度效应对烯烃再吸附及参与二次反应起主导作用,而在烯烃浓度出现峰值后,烯烃的扩散和物理吸附等效应可能起主导作用. 分析烯烃添加的反应器模拟结果发现,考虑烯烃物理吸附作用的动力学模型校正方法不能够正确反映烯烃添加实验的定性规律,而虚拟烯烃分压校正方法能够正确反映烃分布规律并可定量预测烯烃添加对产物分布规律的影响,这对需要尾气循环的F-T合成工业操作具有重要意义.     

Study of activated carbon supported iron catalysts for the Fischer-Tropsch synthesis

Summary Characterization (BET and TPD) and reaction studies were conducted with activated carbon supported iron catalysts (Fe/AC) used for the Fischer-Tropsch synthesis (FTS). The TPD study showed that there existed interactions between metals and the AC surface. Greater association of Cu and K promoters with the AC surface resulted in stronger promoter to surface interaction, which enhanced the H₂ desorption ability of the Cu and K promoted Fe/AC catalyst prepared under vacuum impregnation (VI). Catalytic behavior of a Fe/AC catalyst (VI-15 Fe/2 Cu/2 K/81 AC, in parts per weight) was studied in a 1-liter slurry phase continuous stirred tank reactor. The catalyst presented moderate syngas conversion (44.3-60.6%) and high gaseous selectivity (CH₄, 12.8-15.1% and C₂-C₄, 42.4-46.1%) under 304^oC, 3.0 MPa, 1.1 L(STP)/g-cat/h, and H₂/CO = 2.0 during 166 h of testing. Detectable hydrocarbons up to C₁₈ were formed on the Fe/AC catalyst.     

Effect of Potassium Addition on Coprecipitated Iron Catalysts for Fischer-Tropsch Synthesis Using Bio-oil-syngas

The effects of potassium addition and the potassium content on the activity and selectivity of coprecipitated iron catalyst for Fischer-Tropsch synthesis (FTS) were studied in a fixed bed reactor at 1.5 MPa, 300 o C, and contact time (W=F) of 12.5 gcath/mol using the model bio-oil-syngas of H2/CO/CO2/N2 (62/8/25/5, vol%). It was found that potassium addition increases the catalyst activity for FTS and the reverse water gas shift reaction. Moreover, potassium increases the average molecular weight (chain length) of the hydrocarbon products. With the increase of potassium content, it was found that CH4 selectivity decreases and the selectivity of liquid phase products (C5+) increases. The characteristics of FTS catalysts with different potassium content were also investigated by various characterization measurements including X-ray diffraction, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller surface area. Based on experimental results, 100Fe/6Cu/16Al/6K (weight ratio) was selected as the optimal catalyst for FTS from bio-oil-syngas. The results indicate that the 100Fe/6Cu/16Al/6K catalyst is one of the most promising candidates to directly synthesize liquid bio-fuel using bio-oil-syngas.     

Isothermal Kinetics Modelling of the Fischer-Tropsch Synthesis over the Spray-Dried Fe-Cu-K Catalyst

The isothermal kinetics of the Fischer-Tropsch synthesis (FTS) over Fe-Cu-K spray-dried catalyst was studied in a spinning basket reactor. The experiments were carried out at a constant temperature of 523 K, n(H2)/n(CO) feed ratios of 0.8-2.0, reactor pressures of 1.1-2.5 MPa, and space velocity of 0.556×10-3 Nm3/kgcat·s. Kinetic model for hydrocarbon formation was derived on the basis of simplified carbide mechanism to reduce the number of parameters. Two individual rate constants for methane and ethene were considered. Furthermore, the model was modified empirically by non-intrinsic effect, such as physisorption and fictitious olefin pressures that were taken into account, and the influences of secondary reaction of α-olefins on product distribution. The simulation results showed that the experimental phenomena of FTS and the deviations from ASF distribution, such as the relatively high yield of methane and low yield of ethene observed experimentally could be depicted basically.     

Kinetics studies of nano-structured iron catalyst in Fischer-Tropsch synthesis

Kinetic parameters of nano-structured iron catalyst in Fischer-Tropsch synthesis (FTS) were studied in a wide range of synthesis gas conversions and compared with conventional catalyst. The conventional Fe/Cu/La catalyst was prepared by co-precipitation of Fe and Cu nitrates in aqueous media and Fe/Cu/La nanostructure catalyst was prepared by co-precipitation in a water-in-oil micro-emulsion. Nano-structured iron catalyst shows higher FTS activity. Kinetic results indicated that in FTS rate expression, the rate constant (k) increased and adsorption parameter (b) decreased by decreasing the catalyst particle size from conventional to nano-structured. Since increasing in the rate constant and decreasing in the adsorption parameter affected the FTS rate in parallel direction, the particle size of catalyst showed complicated effects on kinetic parameters of FTS reaction.     

硅对铁基费-托合成催化剂的影响

用共沉淀法制备了一系列不同硅含量的铁基催化剂,采用N2吸附和原位X射线衍射对催化剂进行了表征,在固定床反应器中考察了催化剂的费-托合成反应活性、选择性和稳定性.结果表明,含硅的催化剂具有较大的比表面积和较小的平均孔径,在CO还原及费-托合成反应中生成的碳化铁物种的稳定性比不含硅的催化剂高.在费-托合成反应中,不含硅的催化剂具有较高的初始活性,但易失活;含硅的催化剂具有较低的初始活性,但稳定性较高.Fe7C3是活性最高的碳化铁物种.随着硅含量的增加,催化剂的费-托合成反应更易生成低碳数产物.