Ni/Al_2O_3及La改性Ni/Al_2O_3催化CO浆态床甲烷化性能

采用等体积浸渍法制备了Ni/Al2O3及La改性的Ni-La/Al2O3催化剂,并考察了其浆态床CO甲烷化反应性能。借助XRD、H2-TPR、CO-TPD、H2-TPD等对催化剂进行了表征。结果表明,La助剂改性制备的Ni-La/Al2O3催化剂较Ni/Al2O3催化剂具有更高的CO甲烷化活性,La助剂的添加促进了Ni物种在载体表面的分散,降低了还原温度,增强了催化剂对CO和H2的吸附能力。La助剂的添加次序对甲烷化活性影响较大,采用共浸渍法制备的催化剂具有最佳的甲烷化活性,CO转化率达到96.3%,CH4选择性和时空收率分别达到87.1%和179.6 m L·kg-1·h-1,优于先浸渍Ni后浸渍La或先浸渍La后浸渍Ni制备的催化剂。     

活性炭表面性质对Pd/C常温氧化CO的影响

采用等体积浸渍法制备了活性炭负载Pd催化剂(Pd/C),通过正交实验研究了活性炭的种类、催化剂的制备条件等对活性炭负载钯催化剂上CO氧化性能的影响,得到了最优的制备条件。并通过N2吸附、程序升温脱附(TPD)、程序升温还原(H2-TPR)和透射电镜(TEM)等对催化剂进行了表征。正交实验极差分析表明制备各因素对催化剂氧化CO活性影响的次序为:还原剂>活性炭>还原剂用量>还原温度>还原溶pH值。催化剂表征结果表明活性炭的比表面积和孔径分布不是决定Pd/C催化剂性能的关键因素,活性炭的种类、表面组成和性质对催化剂的性能有显著的影响。其中椰壳炭(AC1)表面羧基的活性较高,同时具有较强的表面碱性,有利于活性金属Pd在载体表面的分散,并提高了Pd与载体之间的相互作用,从而使催化剂具有较高的CO氧化性能。提高Pd的担载量,可显著提高催化剂稳定性。以乙二醇作为还原剂,在pH=10,还原温度为60℃的条件下所制备的0.5%Pd/AC催化剂,在反应温度20℃时连续反应120 h仍可保持CO的全转化。     

聚合物稳定的Au-Pd/TiO2-Al2O3催化剂的还原方法及其催化性能的研究

以PVP为稳定剂，乙醇和K1BH4为还原剂制备了Au-Pd／TiO2-Al2O3催化剂，考察了还原剂对Au-Pd负载型双金属催化剂加氢脱硫性能的影响，并运用XRD，TPD，TPR等技术对催化剂进行表征。结果表明，以乙醇还原的Au-Pd／TiO2-AlO3催化剂的加氢脱硫活性较好。乙醇还原的Au-Pd／TiO2．Al2O3催化剂中Au-Pd之间及活性组分与载体之间的相互作用较强，形成Au-Pd，合金的晶粒较小，活性组分的分散度和活性表面积较大，反应活化能较低，这些均有利于催化剂活性的提高。     

AgO/Al_2O_3催化剂选择还原氮氧化物的研究

对浸渍法和水热共沉淀法制备的AgO/Al2O3催化剂进行了选择还原氮氧化物的研究。结果表明:催化剂制备方法对催化剂的催化效果起重要作用,水热共沉淀法制备的AgO/Al2O3催化剂要比浸渍法制备的更有活性;引入不同的还原剂表现出不同的还原性能,水热共沉淀法制备的AgO/Al2O3催化剂具有更强的抗水抗硫性能。AgO与高比表面积Al2O3之间的强相互作用是水热共沉淀法制备的AgO/Al2O3催化剂具有高选择还原活性的原因所在。催化剂表面吸附的氧气很大程度上促进了氮氧化物的选择性氧化过程。     

稀土对非晶态RuB/膨润土合金催化剂性能的影响

采用气相脉冲法,首次将非晶态RuB/Bn(膨润土)合金催化剂用于催化丙酮常压气相加氢反应。结果表明RuB/Bn催化剂低温下就表现出了很高的活性及生成异丙醇的选择性。稀土元素Nd、Eu、Er的加入提高了RuB合金催化剂的活性,异丙醇的产率也有一定程度的提高。用程序升温还原(TPR)、程序升温脱附(TPD)、等离子体发射光谱(ICP)等方法对催化剂表面性质及含量进行了表征,结果表明稀土元素的加入改变了催化剂的组成,使钌物种易于还原,而且增加了催化剂的氢吸附量。     

在加氢脱氮脱硫过程中载于碳和三氧化二铝的镍-钼崔化剂性能比较

在硫茂、氮苯加氢脱硫、脱氮同时进行的过程中,比较了Ni-Mo/C和Ni-Mo/Al_2O_3硫化物催化剂的催化特性。所用的碳载体由炭黑制备。以碳为载体的催化剂在加氢脱硫过程中具有较高的抗氮苯毒化性能,并具有较高的加氢脱氮活性和选择性。     

一种负载碳化钼催化剂的制备方法及性能研究

采用MoO_3为前躯体,以CH_4/H_2为碳化气,通过程序升温碳化反应装置制备出Mo_2C催化剂,所得催化剂产品用XRD、XPS、SEM进行表征。采用高压微反-色谱实验装置考察了制备的碳化钼催化剂的加氢脱硫反应性能,结果表明:程序升温条件下的局部规整反应可提高催化剂的活性,MoO_3在CH_4/H_2气氛中的还原碳化历程应为MoO_3→MoO_2→MoOxCy→Mo_2C,实验确定的适宜还原碳化温度为600℃。     

ZrO2-Al2O3复合载体的制备方法对Pd基催化剂加氢脱硫性能的影响

采用连续流动微反装置考察了ZrO2-Al2O3复合载体制备方法对Pd基催化荆加氢脱硫性能的影响,并采用XRD,TPR,H2-TPD.NH3-TPD和H2吸附等技术对催化剂进行了表征.结果表明,复合载体的制备方法对Pd基催化剂加氢脱硫性能有较大的影响,与浸渍法相比,溶胶一凝胶法制备的复合载体增强了活性组分与载体的相互作用,有利于Pd分散度的增大和催化剂酸量的增加,从而有利于Pd基催化剂活性的提高.     

锰改性硫酸活化稀土尾矿催化剂的脱硝性能研究

采用浸渍法制备锰改性硫酸活化稀土尾矿催化剂，探究硫酸浓度和锰改性量对催化剂脱硝活性的影响，并通过BET、XRD、H₂-TPR和NH₃-TPD等表征手段对催化剂性能进行分析。结果表明，硫酸浓度为3 mol/L时催化剂的反应温度窗口为350～450℃,在400℃时达到最佳脱硝效率67%;继续添加5%Mn改性后，催化剂的反应温度窗口向低温移动至250～350℃,在此温度范围内N₂选择性保持在70%以上，并在300℃时达到最佳脱硝效率86%。随着硫酸浓度的增加，催化剂的比表面积先增大后减小，孔容、孔径迅速减小。硫酸活化增加了催化剂表面酸性位点的数量，提高了催化剂对NH₃的吸脱附能力。锰元素在催化剂表面以无定形态存在。锰改性催化剂在低温段较强的氧化还原能力是其反应温度窗口较硫酸活化催化剂低的主要原因。     

不同稀土及不同含量的助催化剂对重整反应的影响

考察了不同含量的稀土助剂L a对催化剂比表面积和催化活性的影响,其中以L a含量为1.5%(质量分数)时最佳。催化剂经过973K反应后得到的产物中,H2的量明显大于CO的量,≥1023K时H2/CO的值接近1,这是由于不同温度下催化剂对CH4和CO2活化的程度不同。添加不同稀土助剂催化剂的反应活性与其比表面积有正向关系,比表面积大则活性相对较高,反之则低,其中以L a和Ho为最佳。     

A CeFeO_x catalyst for catalytic oxidation of NO to NO_2

Catalytic oxidation of NO into NO_2 is a promising method for NO_x emission control.The aim of this study was to develop an economic and environmental-friendly catalyst for NO catalytic oxidation.Herein a CeFeO_x complex oxide catalyst for catalytic oxidation of NO was prepared by coprecipitation method.After that the catalytic performance of this catalyst was measured on a fixed-bed reactor.It was found that the intrinsic activity of CeFeO_x was higher than that of CeO_x and FeO_x.The characterization techniques of Brumauer-Emmett-Teller(BET),X-ray diffraction(XRD),temperature programmed reduction with H_2(H_2-TPR),temperature programmed desorption with NO+O_2(NO+O_2-TPD) and X-ray photoelectron spectroscopy(XPS) were performed to investigate the surface area,crystal structure,redox property and NO_x adsorption behavior of the catalyst samples.From the characterization results,it was concluded that the low crystallinity of CeFeO_x promoted the dispersion of active species,as a result,enhancing the redox ability and NO adsorption capacity of CeFeO_x catalyst,which is favorable to NO catalytic oxidation.Furthermore,the presence of much chemisorbed oxygen on CeFeO_x catalyst also made a great contribution to its good catalytic performance.     

稀土在负载型非晶态NiB/Al2O3合金上作用研究

本文采用脉冲技术研究了稀土氧化物对负载型非晶态 Ni B/Al2 O3合金催化剂苯加氢活性和抗硫性能的影响。用 XRD鉴定了非晶态结构 ,用 TPR、TPD表征了催化剂的表面性质 ,用 CO化学吸附法测定了活性镍表面积。实验结果表明 ,非晶态合金催化剂上至少有两种吸附中心 ,稀土氧化物能明显地提高催化剂的苯加氢活性和抗硫性能 ,其原因是稀土氧化物有助于氧化镍的还原 ,从而在反应温度下有更多的活性镍物种被还原 ,稀土氧化物还能使镍物种颗粒细化 ,提高了活性镍面积。     

钕对非晶态NiB/膨润土催化剂性能的影响

采用化学还原法制备了非晶态NiB/膨润土和NiNdB/膨润土催化剂,研究了Nd对催化剂苯加氢活性、热稳定性、抗硫性能的影响。利用ICP、H2-TPD、DSC、XPS、氢化学吸附、CS2中毒等方法对催化剂进行了表征。结果表明,少量Nd可以从结构效应和电子效应两方面影响催化剂性能,使催化剂的加氢活性和抗硫性能提高。而且Nd的存在可以降低合金的自由体积和扩散系数,从而改善了非晶态合金的热稳定性。     

钐对Ni-B/SiO_2非晶态合金催化剂的催化性能及表面性质的影响

本文采用脉冲技术以己二腈气固相常压加氢为探针反应，研究了化学还原法制备的非晶态合金催化剂Ｎｉ－Ｂ、Ｎｉ－Ｂ－Ｓｍ的加氢活性及抗硫性能。并用Ｘ射线衍射（ＸＲＤ）、差示扫描量热分析（ＤＳＣ）、电感耦合等离子发射光谱（ＩＣＰ）、Ｘ射线光电子能谱（ＸＰＳ）、程序升温还原（ＴＰＲ）和程序升温脱附（ＴＰＤ）等手段对催化剂的结构、组成与表面性质进行了表征。实验结果表明，在此催化剂上该反应符合Ｌａｎｇｍｕｉｒ－Ｈｉｎｓｈｗｏｏｄ机理，活性中心座数为２。钐的加入可提高Ｎｉ－Ｂ非晶态合晶的热稳定性、催化活性和抗硫性。其原因可能是钐的给电子效应使合金的组成及表面性质发生了变化。     

Effects of Cerium Dopant on Ni-B Amorphous Alloy Catalysts Used in 2-Ethylanthraquinone Hydrogenation

A series of Ce-doped Ni-B amorphous alloy catalysts were prepared by a KBH4 reduction method, characterized by ICP, BET, XRD, H2-chemisorption, H2-TPD, etc., and tested in the hydrogenation of 2-ethylanthraquinone. The results of characterization show that with the addition of Ce the amount of H2-chemisorption and H2-TPD areas first increases markedly and then decreases with the maximum appears at the atomic ratio of Ce to Ni of 0.036. The hydrogenation activity also shows the same trend. The effects of Ce are attributed to its dispersion of Ni particles, resulting in the formation of more surface Ni centers. However, much higher Ce contents may result in the decrease of the surface Ni contents. After heat treatment at higher temperatures, the amorphous structure of Ni-B is destroyed.     

硅钨杂多酸制备、表征及催化油酸酯化反应合成生物柴油活性研究

采用硝酸酸化-乙醚萃取法制备了一种硅钨杂多酸催化剂,应用扫描电镜(SEM)、红外光谱(FTIR)、X射线粉末衍射(XRD)、程序升温脱附(NH₃-TPD)、热重分析(TG)等手段对催化剂进行了表征,并以甲醇和油酸为反应物,研究了所制备的硅钨杂多酸在催化酯化反应时的活性,考察了催化剂用量、反应时间、反应温度等反应参数对酯化反应产品收率的影响.结果表明:当甲醇与油酸的质量比为3:2,催化剂用量为反应物总质量的1.4 %,反应时间为3.5 h,反应温度为65 ℃时,油酸甲酯的收率最高,为96.45 wt%.      

Catalytic oxidation of formaldehyde over CeO_2-Co_3O_4 catalysts

A series of CeO_2-Co_3O_4 mixed oxide catalysts with different Co/(Co+Ce) atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde(HCHO). Many techniques such as Brumauer-Emmett-Teller(BET), X-ray diffraction(XRD), scanning electron microscopy(FE-SEM), temperature programmed reduction(H_2-TPR), temperature-programmed desorption(O_2-TPD) and X-ray photoelectron spectroscopy(XPS) were used to characterize catalysts. The results of catalytic performance tests showed that the catalyst CeO_2-Co_3O_4 with Co/(Co+Ce) ratio of 0.95 exhibited the best performance, and the temperature of complete oxidation of HCHO was 80 oC. The analytical results indicated that the addition of CeO_2 enhanced the specific surface area of Co_3O_4 and the fine dispersion of both of them. Moreover, the strong interaction between CeO_2 and Co_3O_4 resulted in the unique redox properties, which enhanced the available surface active oxygen and led to high valence state of cobalt oxide species. All those effects played crucial roles in the excellent performance of CeO_2-Co_3O_4 for the HCHO oxidation.     

Effect of praseodymium additive on CeO_2(ZrO_2)/TiO_2 for selective catalytic reduction of NO by NH_3

A series of praseodymium added CeO_2(ZrO_2)/TiO_2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction(XRD), N_2-brumauer-emmett-teller(N_2-BET), NH_3-temperature programmed desorption(NH_3-TPD), H_2-temperature programmed reduction(H_2-TPR), PL spectra, Raman spectra, electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy(XPS), respectively. Influence of preparation method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO_2(ZrO_2)/TiO_2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO_2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO_2 forming the structure of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce~(3+) species, which was favourable for higher catalytic activity.     

Study on Carbon Nanotubes Prepared from Catalytic Decomposition of CH4 over Lanthanum Containing Ni-Base Catalysts

A series of lanthanum containing Ni-base catalysts were prepared by citric acid complex method.Carbon nanotubes (CNT) were synthesized bY catalytic decomposing CH4 over these catalysts and characterized by XRD, TEM and TGA.It is found that the addition of lanthanum can not increase the yield of carbon nanotube, but can make the diameter of carbon nanotube thinner and even.The more the lanthanum addsr, the thinner the diameter of CNTs becomes.With the CNTs prepared on Ni-Mg catalyst, the CNTs prepared on Ni-La-Mg catalyst has better crystallinity and thermal stability.     

Effect of Lanthanum on Catalytic Growth of Carbon Nanotubes from Methane over Nickel-Aluminum Catalyst

The synthesis of carbon nanotubes (CNTs) from methane decomposition by Ni-La-Al (Ni/La/Al = 10: 1:9) and Ni-Al (Ni/A1 = 1:1 ) catalysts at 1023 K was studied.Catalysts were prepared by a co-precipitation method.During the methane decomposition, a part of gases at the exit of the reactor was analyzed by gas chromatography.The experimental results show that doping La into Ni-A1 catalyst improves the catalytic lifetime and the yields of CNTs in the methane decomposition.Some characteristics of CNTs were investigated by TEM and XRD.The analyses show that CNTs deposited on the Ni-La-A1 catalyst have obvious thinner walls, less bend structures and better graphitization than the sample grown over Ni-Al.These results indicate that the introduction of lanthanum into the nickel-aluminum catalyst leads to significant changes in the morphology and microstructures of the CNTs.