沉淀铁催化剂上F-T合成反应的研究

制备了物相组成为 Quartz- Si O2 ,Hermatite- Fe2 O3 和 Fe2 O3 - Iron Oxide的沉淀铁催化剂 ,研究了该催化剂作用上固定床积分反应器中费托合成反应特性 .发现 2 .6MPa,80 0 h-1,H2 /CO=2 /3,2 60℃～ 2 90℃时 ,随着温度的升高 ,CO和 H2 的转化率增大 ,CO2 选择性减小 ;40 0 h-1,65 0 h-1,80 0 h-1低空速和 2 4 0 0 h-1,32 0 0 h-1,40 0 0 h-1,640 0 h-1高空速时 ,随着空速的升高 ,H2转化率、CO转化率选择性下降 ,CO2 的选择性升高 ;2 80℃ ,2 .6MPa,H2 /CO进料比 2 /3,1 /1 ,2 /1时 ,随着 H2 /CO进料比的增加 ,CO转化率 ,H2 /CO利用比和 CH4选择性都增加 ,H2 转化率和 CO2选择性减小 .     

无助剂沉淀铁催化剂上F-T合成的研究

研究了高温条件下无助剂沉淀铁催化剂在固定床积分反应器中的F-T合成反应。实验结果表明在实验条件下,随着温度的升高,CO和H2的转化率明显增大;而空速的增加,H2和CO的转化率下降。在压力2.6MPa,空速0.86L·h-1·(g-Fe)-1,H2／CO=2／3,温度260-280℃时,产物中的烃类主要是C5-11,约占烃类总质量的50％,其次是C2-4,约占烃类总质量的25％,再次是C12+,约占烃类总质量的18％,C1占7％。     

沉淀铁催化剂F-T合成宏观反应动力学模型

该工作为CO+H_2两段法合成汽油工艺中的一般F-T合成宏观反应动力学研究。采用原颗粒Fe-Cu—K沉淀铁催化剂与内循环反应器。实验设计为正交法,其温度变化范围为:230～260C;压力:1.5～3.0MPa;空速:250～1000h~(-1);原料气中H_2/CO:1.0～2.5。在此研究范围内,观察到水的抑制作用,但无二氧化碳的抑制作用。宏观动力学模型与实验数据拟合得较好且与本征动力学的形式相同,即 -R_(H_2+CO)=(1.568×10~2exp(-8839/RT)p_(H_2)p_(CO))/(p_∞+6.819×10~(-8)exp(8556/T)p_(H_2O))     

费托合成沉淀铁催化剂性能的研究进展

费托合成（F-F合成）是实现煤间接液化技术的重要环节之一,其关键是开发高活性、选择性和稳定性的催化剂。目前应用的费托合成催化剂主要有铁基和钴基催化剂。铁基催化剂因价格低廉、催化活性和水煤气变换反应（WGS）活性高以及助剂效果明显,而在费托合成催化剂中占有重要的地位。本文对近几年铁基催化剂的特点和发展状况进行了评述,着重分析了催化剂制备过程、助剂和还原活化对其活性和选择性的影响。     

超声波法研究F-T合成铁基催化剂机械强度

采用超声波法研究了微颗粒催化剂磨损机械强度及其磨损机制,考察了超声介质、超声功率、固液比和超声时间等对磨耗率的影响,并在相同测试条件下,比较了熔铁催化剂和沉淀铁催化剂磨耗强度。结果表明,熔铁催化剂还原后耐磨强度略降,与此相反,沉淀铁催化剂还原后耐磨强度略有提高。由球磨法得到的熔铁催化剂存在较多微细粉末的粘附与团聚,影响测定结果,但熔铁催化剂的耐磨强度高于沉淀铁催化剂。基于形态和粒度分布的研究表明,超声波作用下熔铁催化剂主要磨损机制为剥层磨损,沉淀铁催化剂为体断裂或破碎机制。     

费托合成熔铁催化剂对液体产物的影响

实验考察了温度、压力、H2/CO和空速等不同操作条件对固定床熔铁催化剂费托合成液态产物的影响,得出了液态产物在不同操作条件下的时空产率、烃类产率、含碳量(C5～C13)、烯烷比及正构烷烃与支链烷烃(正支比)的一些变化规律。     

无梯度反应器中沉淀铁催化剂FT合成反应研究

在转篮式无梯度反应器中对喷雾干燥沉淀铁催化剂进行了 Fischer- Tropsch( FT)合成反应研究 .结果表明 :反应温度对 C1～C2 烷烃生成速率的影响比对 C3 ～ C4烷烃的大 ,对 C3 ～ C4烯烃生成速率的影响比对 C3 ～ C4烷烃的大 ;H2 /CO进料比对 C3 ～ C4烷烃和 C2 ～ C4稀烃的作用是先促进后抑制 ;提高反应压力对 C1～ C4烷烃和 C2 ～ C4烯烃的生成具有促进作用 .产品的烃分布为典型的双α分布 ,交点在 C6,α1为 0 .5 5 ,α2 为 0 .89     

熔铁催化剂超临界相费托合成的研究

在固定床反应器上进行了熔铁催化剂在超临界介质存在条件下的费托合成,并与气相费托合成进行对比。结果表明,由于超临界介质具有类似气体的传质速率和类似液体的溶解能力和热容,减小了催化剂床层过热,减少了催化剂床层积炭,增加了合成气在催化剂表面浓度,促进了产物的脱附,使CO转化率提高,α-烯烃选择性和C5＋选择性增加,甲烷选择性减小。实验考察了温度、压力、合成气比例、合成气空速对超临界相费托合成反应的影响。发现当反应温度或压力低于介质的临界温度及压力时,反应性能迅速下降,说明介质仅在其临界点以上才表现出优良的超临界性能。其他反应条件对超临界相费托合成反应性能的影响类似气相费托合成。     

浆态相费托合成反应铁基催化剂的磨损研究

在催化剂磨损现象和强度理论的基础上,对浆态相费托合成反应中的铁催化剂的磨损机制进行了描述,侧重对系列雷尼铁催化剂的磨损规律加以研究,结果表明雷尼铁的磨损是因为其发达的孔结构,反应条件下沿狭缝形的孔发生破裂,但是并不致使继续粉化,而且其粒度的变化对浆态相费托合成反应活性影响很小,反应结束后的分离性能也显著优于沉淀铁催化剂。     

喷雾干燥铁催化剂F-T合成反应的研究

采用转环式无梯度反应器对沉淀 -喷雾干燥技术相结合制备的 Fe- Cu- K- Si O2 催化剂在反应温度 2 5 0℃～ 2 80℃ ,压力 0 .5 MPa～ 1 .5 MPa,H2 /CO比 0 .1 9～ 1 .35和原料气空速 1 0 0 0h-1～ 2 5 0 0 h-1的条件下对 Fisher- Tropsch合成反应性能进行了考察 .结果表明 ,该催化剂具有较高的 F- T反应活性和水煤气交换 ( WGS)反应活性 ,产物烃分布显示出高的烯烃选择性 ,说明该条件有利于初级烯烃的脱附和低碳烃的生成 ,一定程度上减少了烯烃再吸附的链增长反应 .还考察了各种反应条件对产物碳数分布的影响 ,并观察到了运行过程中催化剂较低的失活速率 .     

费托合成催化剂的研究进展

介绍了费托合成的研究现状,分析了费托合成催化剂的组成,重点评述了恬性组分、载体、助剂等因素在催化剂制备过程中对催化剂的活性、选择性等方面的影响,并对费托合成催化剂研究领域存在的问题进行了探讨。     

Attrition resistance of spray-dried iron F–T catalysts: Effect of activation conditions

The focus of the research reported herein was to investigate the effects of phase changes, as occur during Fe catalyst activation and Fischer–Tropsch synthesis, on Fe catalyst attrition resistance. Different activation conditions (CO, H₂ or syngas) were applied prior to attrition testing to a selected spray-dried Fe catalyst containing 9.1 wt.% binder SiO₂, which had been shown to have the highest attrition resistance in our early study of calcined catalysts. Although, XRD indicated that different Fe phase compositions resulted in the differently activated catalyst samples, chemical attrition was not observed for any of the samples. The BET surface areas of the activated samples were smaller than that of the calcined precursor but no significant changes in pore volume and particle size were found. The attrition resistances of the differently activated catalyst samples were found to be similar to that of the calcined catalyst for this spray-dried Fe catalyst. Attrition resistance was found previously to be governed by catalyst particle density, which has been shown earlier to relate to the SiO₂ network in catalysts. It is therefore suggested that the type and concentration of SiO₂ that is incorporated during the preparation of spray-dried Fe catalysts have a much more significant impact on catalyst attrition than Fe phase change during activation in the presence of CO, H₂ or H₂+CO.     

蔗糖基准校准红外吸收法测定非合金钢中超低碳的空白值

按照GB/T 20126-2006测定非合金钢中超低碳含量时,由于分析所使用的纯铁助熔剂没有准确定值,所以无法计算出真正的空白值加以扣除,影响测定结果的准确性。通过实验,采用二次坩埚预处理技术,有效地扣除了空白值;采用蔗糖基准建立了工作曲线,准确地测定了纯铁中质量分数在0.000 6%~0.002 4%的超低碳,标准偏差为0.000 028%~0.000 078%。     

Co基催化剂用于费托蜡合成的研究

以SiO2为载体,分别制备了添加Zr,Mn及Ce助剂的三种钴基催化剂。通过反应装置上评价,含Zr助剂的催化剂反应活性和蜡产率最高。考察了不同温度,压力,空速对添加Zr助剂的催化剂催化性能的影响。结果表明：随着温度升高,蜡产率先增加后减少;高压和低空速适合蜡的生成。     

Pathways for CO2 Formation and Conversion During Fischer–Tropsch Synthesis on Iron-Based Catalysts

CO₂ reaction and formation pathways during Fischer–Tropsch synthesis (FTS) on a co-precipitated Fe–Zn catalyst promoted with Cu and K were studied using a kinetic analysis of reversible reactions and with the addition of ¹³C-labeled and unlabeled CO₂ to synthesis gas. Primary pathways for the removal of adsorbed oxygen formed in CO dissociation steps include reactions with adsorbed hydrogen to form H₂O and with adsorbed CO to form CO₂. The H₂O selectivity for these pathways is much higher than that predicted from WGS reaction equilibrium; therefore readsorption of H₂O followed by its subsequent reaction with CO-derived intermediates leads to the net formation of CO₂ with increasing reactor residence time. The forward rate of CO₂ formation increases with increasing residence time as H₂O concentration increases, but the net CO₂ formation rate decreases because of the gradual approach to WGS reaction equilibrium. CO₂ addition to synthesis gas does not influence CO₂ forward rates, but increases the rate of their reverse steps in the manner predicted by kinetic analyses of reversible reactions using non-equilibrium thermodynamic treatments. Thus the addition of CO₂ could lead to the minimization of CO₂ formation during FTS and to the preferential removal of oxygen as H₂O. This, in turn, leads to lower average H_2/CO ratios throughout the catalyst bed and to higher olefin content and C₅₊ selectivity among reaction products. The addition of ¹³CO₂ to H₂/¹²CO reactants did not lead to significant isotopic enrichment in hydrocarbon products, indicating that CO₂ is much less reactive than CO in chain initiation and growth. We find no evidence of competitive reactions of CO₂ to form hydrocarbons during reactions of H₂/CO/CO₂ mixtures, except via gas phase and adsorbed CO intermediates, which become kinetically indistinguishable from CO₂ as the chemical interconversion of CO and CO₂ becomes rapid at WGS reaction equilibrium.     

Effect of the Ratio of Precipitated SiO2 to Binder SiO2 on Iron-based Catalysts for Fischer–Tropsch Synthesis

The effects of the ratio of precipitated SiO₂ to binder SiO₂ (Si(P)/Si(B)) on the reduction, carburization and catalytic behavior of precipitated Fe–Cu–K–SiO₂ catalysts for Fischer–Tropsch synthesis (FTS) were investigated by N₂ physisorption, temperature-programmed reduction/desorption (TPR/TPD) and Mössbauer effect spectroscopy (MES). FTS performances of the catalysts were tested in a continuous stirred tank reactor (CSTR). It is found that the increase of Si(P)/Si(B) ratio (Si(P)/Si(B) = 0/25 ～ 15/10) decreases the crystallite size of the catalysts, improves the surface basicity, enhances the reduction and carburization of the catalysts, and increases the activity of the catalyst. However, when Si(P)/Si(B) ratio is further increased (Si(P)/Si(B) = 25/0), the catalyst exhibits a restrained reduction and carburization behavior, which may be attributed to the stronger metal–support interaction. Based on the present work, a catalyst with a suitable ratio of Si(P)/Si(B), for example Si(15)/Si(10) displays an optimal FTS performances.     

利用硅灰石生产白炭黑的实用技术研究

研究了沉淀法生产白炭黑的工艺技术 ,制定了硅灰石生产白炭黑的实用工艺流程 ,经检验白炭黑产品达一级品水平     

Activity and selectivity control in iron catalyzed Fischer-Tropsch synthesis

We present results of a catalyst structure-function study that supports a CO hydrogenation model with -olefins formed as the principal primary products and n-paraffins formed during secondary hydrogenation reactions. The interplay of catalyst composition and reaction environment controls the extent of secondary reactions. Catalysts that contain mainly oxidic phases or carbides with large concentrations of excess matrix carbon favor secondary reactions. The relative concentrations of oxide and carbide phases depends on the ease of reduction of the catalyst, which can be changed by cation substitutions. For example, cobalt substitution into Fe₃O₄ lowers the reduction temperature by 20 ° C. Excess matrix carbon has been intentionally introduced (by treatment in high temperature H₂/CO) into model iron carbide catalysts produced by laser synthesis. Increased paraffin selectivity as matrix carbon is introduced suggests the influence of the diffusion constraints on product selectivity. Alkali promotion will affect secondary hydrogenation pathways. We illustrate how catalysts with low levels of alkali become increasingly more selective to paraffins at high conversions (and high effective H₂/CO ratios).Reaction environment also controls catalyst composition and selectivity. Mossbauer spectroscopy on spent catalysts suggests that oxide/carbide phase formation in iron catalysts are sensitive to reactor configuration (extent of backmixing). In integral fixed bed reactors, catalysts partition into carbide phases in the front of the bed but show increasing amounts of oxide near the exit, whereas the catalysts in the stirred tank reactor remain all carbides. Product selectivities reflect the phase differences.Other examples illustrating secondary hydrogenation phenomena will be presented.