助剂对Co／HMS催化剂结构和F-T合成性能的影响

详细研究了钍、锆、锗及铈助剂对钴质量分数为15％的Co／HMS催化剂结构、 F-T合成CO转化率、CO2选择性及烃分布的影响,结果表明：钍能适当提高F-T合成 活性,且低温下具有较强的链增长能力;锆、锗、铈降低了催化剂CO转化率,催化 剂加氢能力变强,导致低碳烃增加较快,汽柴油馏分段减低,相应的链增长能力降 低,并以锰和铈较为明显;XRD,TPR及TG表征表明：锆和铈可提高催化剂Co还原度 ,但F-T合成反应时金属Co易披氧化,反应中金属Co量明显减少,CO转化率降低, 并以铈最为显著;Th助催化剂Co还原度稍有减低,Co分散度高于Co／HMS,且反应 中金属Co较为稳定,Co转化率得以提高;添加Mn助剂后,催化剂难以还原,反应中 活性相金属Co量较小,CO转化率较低．     

中孔分子筛负载的钴基催化剂F-T合成反应研究

以中孔分子筛HMS-2为载体,浸渍法制香钴质量分数为15.00%的钴基催化剂,F-T合成反应研究表明：载体焙烧时间对F-T合成反应性能影响不大;Co/HMS-2催化剂的F-T合成反应在运行141.00h达到483.00K后,在H2/CO摩尔比为2.00,压力2.00MPa,空速500.00h^-1反应条件下,CO转化率达到88.00%,烃选择性保持在98.00%左右,烃分布中C5^+含量可达85.00%左右,进一步运转了384.00h,CO转化率仅下降了9.00%,而烃选择性和烃分布几乎不变,说明Co/HMS-2催化剂F-T合成反应性能和稳定性优异。载体中孔结构在473.00K催化剂开始F-T合成反应24.00h后已经塌陷,随后催化剂结构趋于稳定。     

还原气氛对CoFe/SBA-15催化剂F-T反应性能的影响

考察了不同还原气氛处理CoFe/SBA-15催化剂对F-T反应性能的影响。结果表明,H2气氛下有利于六方钴的生成;催化剂的活性取决于钴含量,随着钴含量的增加,F-T反应中CO转化率增加,C5+选择性增加。随着铁含量的增加,催化剂表现了较高的CO2选择性。CO还原有利于立方钴的生成,导致催化活性相比H2还原的催化剂活性要低。同时CO还原容易产生积炭使催化剂的钴活性位被覆盖,导致甲烷选择性随着钴含量增加而升高。但碳化铁的生成有利于提高20Fe/SBA-15催化剂的活性,有利于低碳烃生成及C2~4烃烯烷比增加。     

浆态床F-T合成反应中反应参数对e/Cu/K/SiO2催化剂性能的影响

 用喷雾干燥法制备了微球状Fe/Cu/K/SiO2催化剂,并在不同的反应条件下对其在浆态床F-T合成反应中的催化性能进行了评价. 结果表明,反应温度和原料气H2/CO比的调变对催化剂运行稳定性的影响较大,反应初始阶段加入的液体石蜡介质对催化剂运行稳定性的影响不大. 原料气空速的增加可有效地提高反应的总烃时空产率,但同时CO转化率会明显降低,且重质烃选择性下降; 低H2/CO比的原料气有利于在保持合适的转化率的同时提高重质烃的选择性,并可明显提高总烃的时空产率; 提高系统压力可增大催化剂的催化活性,改善重质烃的选择性; 而提高反应温度尽管可明显提高催化剂活性,但同时也会促进WGS反应的发生,降低重质烃的选择性. 因此,浆态床F-T合成反应中操作参数的适当调变可使催化剂活性、产物烃分布和烃产率得到有效优化,最大限度地获得目的产物.     

Effects of calcination and reduction temperature on the performance of Co-Pt-ZrO2/γ-A12O3 catalysts for Fischer-Tropsch synthesis

采用浸渍法制备了Co-Pt-ZrO2/γ-Al2O3催化剂,对其进行了BET、XRD和TPR等表征,并在浆态床反应器上考察了焙烧温度和还原温度对催化剂费托合成反应性能的影响.结果表明,焙烧温度过高,容易造成Co物种和载体间的相互作用增强,使部分氧化钻颗粒聚集或烧结,导致催化剂的F-T合成反应活性和C5+烃选择性降低.还原温度较低时,钴物种不能充分还原,CO加氢活性低,甲烷选择性高,重质烃选择性低;还原温度过高,则可能造成活性物种的烧结,反而降低了催化剂的活性和重质烃选择性.在原料气n(H2)/n( CO)=2.0、483 K、2.4 MPa和空速3.6 L/( gcat·h)的条件下,31.08％ Co～0.11％Pt ～ 7.16％ ZrO2/Al2O3催化剂在673 K焙烧.纯H2下653 K还原后,其费托性能最佳;CO转化率为27.0％,C5+的选择性为83.0％.     

SBA-15的疏水改性及其对钴基催化剂费-托合成催化性能的影响

利用甲硅烷基化作用制得了不同疏水基团(甲基、二甲基和三甲基)改性SBA-15载体,采用等体积浸渍法制备了质量分数为5%的一系列负载型钴催化剂。结合BET、FT-IR、29Si CP MAS NMR、XRD和H2-TPR等表征手段,考察了SBA-15疏水改性对钴基催化剂物相结构、还原行为以及费-托合成催化性能的影响。催化剂在固定床反应器中在p=2.0 MPa,t=200~250℃,H2和CO体积比为2和GHSV=1 000 h-1的条件下进行评价。结果表明,相对于未改性SBA-15负载钴催化剂,疏水基团改性SBA-15负载钴催化剂的还原度增加,CO转化率提高;Co3O4晶粒粒径增大,难还原钴物种减少,CH4选择性降低,C5+烃选择性增加。     

结构助剂SiO2、Al2O3对铁基催化剂浆态床F-T合成性能的影响

采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球状Fe/Cu/K/SiO2和Fe/Cu/K/Al2O3催化剂，研究SiO2和Al2O3作为结构助剂对铁基催化剂吸附行为、炭化行为及F-T合成反应性能的影响。表征结果表明,与Al2O3相比较，SiO2抑制了H2的吸附，但促进了CO的吸附，有利于催化剂的炭化。催化剂在260℃、1.5MPa、H2/CO=0.67和2000h-1下的浆态床F-T合成反应评价表明，Fe/Cu/K/SiO2催化剂具有较高的F-T合成活性、高的水煤气变换反应（WGS）活性，且其烃产物选择性明显向高炭数方向偏移，而Fe/Cu/K/Al2O3催化剂则表现出较低的F-T合成活性、低的水煤气变换反应（WGS）活性和高的轻质烃选择性。但Fe/Cu/K/Al2O3催化剂比Fe/Cu/K/SiO2催化剂具有更好的运行稳定性。     

介孔氧化硅球负载钴基催化剂在费托合成中的应用

以介孔氧化硅空心球(HMSS)为载体, 采用双溶剂法浸渍硝酸钴溶液制备了高分散度的钴催化剂, 并表征了催化剂中Co3O4颗粒的负载情况和费托(F-T)反应性能. 结果表明: Co3O4颗粒在介孔硅球孔道内形成100～200 nm左右分散良好的簇团, 将催化剂压碎和刻蚀后的透射电子显微镜(TEM)证实, 这些簇团是由尺寸约为10～15 nm大小均匀的Co3O4单分散颗粒组成, 这些单分散颗粒锚定在介孔硅球孔道内, 彼此之间被相邻孔壁隔开; 催化剂中钴-硅作用很弱, 在600 K下即可被还原; F-T反应评价表明, 所得产物保持了良好的烃分布, 主要集中于C5～C18烃, 选择性在60%左右, C5＋选择性达到80%以上.     

Cu、K助剂对FeMn/SiO2催化费托合成的影响

研究了Cu、K助剂对共沉淀型FeMn/SiO2催化剂还原行为、吸附行为及费托(F-T)合成活性和选择性的影响. Cu助剂以与Fe、Mn、SiO2共沉淀的方式引入, 而K助剂是在喷雾干燥前均匀加入沉淀浆料引入的. 结果表明, Cu可明显提高催化剂的还原性能, K助剂能促进催化剂在CO中的还原但抑制在H2中的还原, 而同时加入Cu和K会进一步促进催化剂在H2或CO中的还原; Cu助剂能促进H2吸附而K助剂对H2吸附无明显影响; Cu在一定程度上提高了F-T合成活性, 缩短了反应诱导期, K明显促进了CO的转化而相对抑制了H2的转化, 并且延长了反应的诱导期, Cu与K协同作用不仅提高反应的转化率而且缩短了反应的诱导期; K使得烃产物平均分子量增加, Cu单独对烃产物分布影响不明显, 而与K共同作用会进一步增加烃产物的分子量.     

工业固定床Fe-Cu-K催化剂浆态床F-T合成适应性研究

采用连续搅拌釜式反应器,在接近F-T合成实际工况下考察了工业固定床Fe-Cu-K催化剂浆态床F-T合成反应性能，研究反应温度、压力、原料气空速和氢碳摩尔比等操作参数对催化剂反应活性、产物选择性和稳定性的影响，实验总运转时间达2 500 h；同时采用扫描电镜技术（SEM）对催化剂的抗磨损性能进行了研究，结果表明，操作参数对催化剂的活性、选择性和目标产物产率有较大的影响，工业固定床Fe-Cu-K催化剂具有一定的抗磨损性能，F-T合成烃产物分布合理；催化剂具有较高的稳定性，在589 h的稳定条件运行内，催化剂的失活速率为0.23%/d（以CO转化率的降低计）；在整个运行期间CH4选择性维持在较低的水平。     

超临界和近临界条件下Fischer Tropsch合成研究：溶剂的影响

研究了超临界和近临界条件下费托合成过程中溶剂对反应行为的影响。反应在固定床反应器中进行，催化剂为Co/SiO2，所选择的溶剂有两类：纯溶剂（正戊烷和正己烷）和混和溶剂（由正己烷和少量的C5~10烃组成）。结果表明,正己烷分压对CO转化率影响很小，但是产物中1 烯烃含量随正己烷分压增加而增加，超临界条件下1 烯烃含量明显高于非临界条件下。溶剂的种类对CO转化率、CH4和CO2选择性以及产物炭分布影响不大。这一结果表明为了减少溶剂用量，对含有适量轻组分（C5~10）的正己烷溶剂进行循环使用是可行的。结果同时表明与正己烷相比，混和溶剂（25%正己烷和75%正葵烷）具有较高的1 烯烃选择性。     

超临界相由合成气合成低碳醇的研究

选择有代表性的Ｃｕ－Ｃｏ,Ｚｎ－Ｃｒ和ＺＲ－Ｍｎ体系为催化剂,研究了超临界条件下由合成气 民低碳醇的规律及提高产物中Ｃ２＋ＯＨ含量的可能性。结果表明,三种催化剂上超临界相合成醇反应的ＣＯ转化率都比气相合成醇反应的高。Ｃｕ－Ｃｏ催化剂上超临界相合成反应的醇选择性低于气相合成者,但合成醇的产物与气相合成的相同,且均符合Ｓｃｈｕｌｚ－Ｆｌｏｒｙ分布。Ｚｎ－Ｃｒ和Ｚｒ－Ｍｎ催化剂上的产物分布不符合Ｓｃｈｕ     

Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH₄ and CO₂ as well as higher yield of C₅₊ products were achieved. The optimal performance of a 92% CO conversion and a 65% C₅₊ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C₅₊ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO₂ byproduct, and higher yield of C₅₊ products.     

低温高活性熔铁催化剂上的超临界相费托合成反应

在固定床反应器中超临界相条件下研究了熔铁催化剂上的费托合成反应,发现在超临界介质中反应物和产物更容易扩散,较好地抑制了催化剂表面非活性碳的沉积,从而提高了费托合成反应中的CO转化率和烯烃选择性,增加了链增长因子,降低了甲烷选择性.同时,考察了超临界介质、反应温度、压力、H2/CO比和空速等条件对费托合成反应的影响.结果表明,C5-8正构烷烃在催化剂活性温度下都是适宜的超临界介质.当温度和压力都在介质的临界点以上时,介质表现出较好的传质与传热性能,可改善费托合成反应性能.     

Cr-free Co-Cu/SBA-15 catalysts for hydrogenation of biomass-derivedα-,β-unsaturated aldehyde to alcohol

Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of bio-mass-derived α-, β-unsaturated aldehyde (furfural) to value-added chemical furfuryl alcohol (FOL). Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings (2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray dif-fraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, ener-gy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemi-sorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the cata-lyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.     

Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline

Selectively converting CO and H2 to gasoline product(isoparaffin and olefin) in one step still remains a great challenge. We demonstrate effective H-USY zeolite supported nano-cobalt bifunctional catalysts for this catalytic reaction, which are prepared by the novel physical sputtering process. Particles of the sputtered cobalt exist in nano-level and are well-dispersed on acid USY zeolite. Easy activation of the loaded nano-cobalt is also achieved in a low-temperature hydrogen reduction atmosphere. In the tandem catalytic reaction, the sputtered bifunctional Co/USY catalyst exhibits a much higher CO conversion and higher isoparaffin selectivity than the conventional impregnated one. Compared with H-Mor, H-Beta and other zeolites supported catalysts, H-USY zeolite supported cobalt catalyst shows the clearest promotional effect on the activity of FischerTropsch synthesis. The described synthesis herein provides a new pathway to solve the problem caused by the strong metal-support interaction(MSI) in heterogeneous catalysis.     

Effect of cobalt weight content on the structure and catalytic properties of Co/CNT catalysts in the fischer–tropsch synthesis

Cobalt-based Fischer–Tropsch synthesis (FTS) catalysts containing 1 to 40 wt % cobalt supported on multi-walled carbon nanotubes (CNTs) have been investigated. The CNTs have been characterized by low-temperature nitrogen adsorption, scanning electron microscopy, and X-ray photoelectron spectroscopy. All catalysts have been prepared by impregnating, with an ethanolic solution of cobalt nitrate, the CNTs preoxidized with concentrated nitric acid and have been tested in the FTS at 220°C and atmospheric pressure. Correlations have been established between the cobalt weight content of the catalyst and the Co particle size determined by transmission electron microscopy and X-ray diffraction. The Co content and particle size have an effect on the activity and selectivity of the catalyst and on the target fraction (C₅₊) yield in the FTS. The highest CO conversion is observed for the catalyst containing 20 wt % Co; the highest selectivity and activity, for the catalyst containing 5 wt % Co; the highest C₅₊ yield, for the catalyst containing 10 wt % Co.     

Effect of MgO promoter on Ni-based SBA-15 catalysts for combined steam and carbon dioxide reforming of methane

A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and their catalytic performances for the reaction of combined steam and carbon dioxide reforming of methane were investigated in a continuous flow microreactor. The structures of the catalysts were characterized using the XRD, H2-TPR and CO2-TPD techniques. The results indicated that the CO selectivity for this reaction was very close to 100%, and the H2/CO ratio of the product gas could be controlled by changing the H2O/CO2 molar ratio of the feed gas. The simultaneous and plentiful existing of steam and CO2 had a significant influence on the catalytic performance of the 10%Ni/SBA-15 catalyst without modification. After reacting at 850 °C for 120 h over this catalyst, the CH4 conversion dropped from 98% to 85%, and the CO2 conversion decreased from 86% to 53%. However, the 10%Ni/3%MgO/SBA-15 catalyst exhibited a much better catalytic performance, and after reacting for 620 h, the CO2 conversion over this catalyst dropped from 92% to around 77%, while the CH4 conversion was not decreased. Oxidation of the Ni0 species as well as carbon deposition during the reaction were the main reasons for the deactivation of the catalyst without modification. On the other hand, modification by the MgO promoter improved the dispersion of the Ni0 species, and enhanced the CO2 adsorption affinity which in turn depressed the occurring of carbon deposition, and thus retarded the deactivation process.     

Synthesis and characterization of niobium-promoted cobalt/iron catalysts supported on carbon nanotubes for the hydrogenation of carbon monoxide

Bimetallic Co /Fe catalysts supported on carbon nanotubes( CNTs) were prepared,and niobium( Nb) was added as promoter to the 70 Co ∶30Fe /CNT catalyst. The physicochemical properties of the catalysts were characterized,and the catalytic performances were analyzed at the same operation conditions( H_2 ∶CO( volume ratio) = 2 ∶1,p = 1 MPa,and t = 260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane,and the selectivity to C_(5+) increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C_(5+). Meanwhile,a decrease in methane selectivity is observed.     

CO removal by two-stage methanation for polymer electrolyte fuel cell

In order to remove CO to achieve lower CO content of below 10 ppm in the CO removal step of reformer for polymer electrolyte fuel cell （PEFC） co-generation systems, CO preferential methanation under various conditions were studied in this paper. Results showed that, with a single kind of catalyst, it was difficult to reach both CO removal depth and CO2 conversion ratio of below 5%. Thus, a two-stage methanation process applying two kinds of catalysts is proposed in this study, that is, one kind of catalyst with relatively low activity and high selectivity for the first stage at higher temperature, and another kind of catalyst with relatively high activity and high selectivity for the second stage at lower temperature. Experimental results showed that at the first stage CO content was decreased from 1% to below 0.1% at 250-300 ℃, and at the second stage to below 10 ppm at 150-185 ℃. CO2 conversion was kept less than 5%, At the same time, influence of inlet CO content and GHSV on CO removal depth was also discussed in this paper.