Molecular sieve catalysts are one of the most studied fluidized bed catalysts.Molecular sieve microsphere catalysts are typically prepared by spraydrying processes,which used double aluminum-based sol,silica-aluminum composite sol,phosphorus-aluminum sol,etc.as binders in industry.The fluidized bed catalysts required not only good catalytic performance,but also superiorattrition resistance,favourable sphericity and appropriate particle size distribution to match the actual industrial manufacturing.The attri-tion resistance,particle size distribution,sphericity and catalytic performance of molecular sieve catalysts are significantly affected by the selection of binders and supports,the slurry preparation processes,the inlet and outlet temperatures of the spraydrying processes,the atomizer speed and the post-processing of the catalysts.The current research progresseson improving the attrition resistance of fluidized bed molecular sieve catalysts(FCC catalysts and MTO catalysts are taken as examplesin this paper)are summarized from three aspects including optimization of catalyst slurry components,optimization of spraydrying proces-ses and post-processing of catalysts,and provide some references for the research & development of other attrition resistant fluidized bed catalysts.
Aldol condensation of furfural with cyclopentanone is one of the important steps in preparation of the high-quality biofuels.The synthesis of renewable biofuels from biomass furfural and cyclopentanone is sustainable and meets the requirements of green chemistry.However,the catalytic mechanism of this reaction are not very clear.Under different catalysis,two products can be obtained,2,5-bis(2-furanylmeth-ylene)cyclopentanone(F2Cp)and 2-(2-furanylmethylene)cyclopentanone(FCP).In this paper,the catalytic performances of acid catalyst,base catalyst and acid-base bifunctional catalyst used in the reac-tion for target product of F2Cp were analyzed.The analysis shows that both acidic Al2O3 catalyst and acid-base bifunctional Na-HAP catalyst have better catalytic performance.The microwave radiation method can increase the reaction rate under free solvent.On this basis,the catalytic mechanism is described and ana-lyzed.The mechanism analysis shows that the acid-base synergism is beneficial to the aldol condensation reaction.Therefore,the design and preparation of solid acid-base bifunctional catalysts with appropriate acid-base ratio is the focus of the follow-up study of this reaction,and also provide some references for the aldol condensation reaction of other aldehydes or ketones.
5％TiO2-nMoO3 catalysts with different amounts of MoO3 were prepared by molten salt roasting and impregnation.The hydrodesulfurization activity of the catalysts was evaluated by using dibenzothio-phene/cyclohexane solution as model reactant in a self-made high pressure micro reactor.XRD,BET,H2-TPR and NH3-TPD were used to characterize the phase structure,specific surface area,reduction per-formance and surface acidity of the catalysts.The results showed that when the reaction pressure was 4.0 MPa,liquid hourly space velocity was 10 h-1,and the volume ratio of hydrogen to oil was 600∶1.the hydrodesulfurization activity increased firstly and then decreased with increasing of MoO3 amount.When the amount of MoO3 was 15％,the maximum hydrodesulfurization conversion of dibenzothiophene could reach 30.08％,95.35％and 97.42％at 280 ℃,300℃and 320 ℃.The desulfurization of dibenzothio-phene over 5％TiO2-nMoO3 catalyst was mainly carried out by direct desulfurization.
The performance of ruthenium catalysts supported by different carriers based on impregnation method in liquid hydrogenation of 4,4'-diaminodicyclohexyl methane to trans-trans isomeric PACM was investigated,and the influence of the second metal additive on the performance of catalysts was studied.The results showed that the activity and selectivity of catalysts were significantly improved after the addi-tion of metal Re,and the optimal loading ratio of Ru∶Re is 5∶1.The content of PACM trans-trans isomer is less than 20％.The catalyst has good stability.
Copper metal organic framework material(Cu-MOF)was synthesized by steam induction method,and cerium was introduced into the Cu-MOF skeleton structure by impregnation method to obtain com-posite precursor.Then,a new type of Cu-based composite oxide was prepared by high-temperature heat treatment.It was found that the doping of cerium could modify the crystal structure of Cu-based composites.As well-prepared catalysts,the effect of cerium loading was investigated on the catalytic performance of Cu-Ce composite oxides,and to obtain the optimal preparation conditions of the catalyst.The optimized composite catalyst exhibited efficient catalytic oxidation activity for CO under 180 ℃ conditions,with a space velocity of 50 000 h 1 and CO removal efficiency of over 99％.In addition,the addition of TiO2 in the synthesis of Cu-MOF could modulate the formation of CuO and promote the catalytic performance of the catalyst for CO oxidation.
TiO2 carrier has good catalytic performance,stable physical and chemical properties and non-toxic characteristics.The advantages of titanium dioxide as denitration catalyst carrier are introduced on the basis of catalyst carrier loading active components.The forming of titanium dioxide carrier and appli-cation of titanium dioxide carrier in denitration industry were reviewed.Pure titanium dioxide and titanium dioxide carrier loaded with vanadium,tungsten,rare earth cerium,etc.as denitration catalysts are two main applications of TiO2.The future development direction will focus on improving the service life of tita-nium dioxide carrier,preventing titanium dioxide earrier poisoning and adding more active components,and improving the service life of denitration catalyst and denitration efficiency to meet the increasingly stringent environmental requirements of ultra-low emissions of flue gas and mobile source tail gas.
BiOBr nanosheets and BiOBr microspheres were prepared by hydrothermal method using sodium hydroxide and cetyltrimethyl ammonium bromide as morphology guides.The CdS nanoparticles were loaded on the BiOBr surface by the hydrothermal deposition method.The morphology,structure,and band structure of the catalyst samples were characterized by SEM,XRD,and UV vis DRS,respectively.The activity of the samples was evaluated by the photocatalytic reduction of CO2 in cyclohexanol under visible light.The results show that the main products are cyclohexanone(CH)and cyclohexyl formate(CF).The activity of the hierarchical microsphere CdS/BiOBr composites is higher than that of the nanosheet structure composites.After four repeats,the activity of the catalyst did not decrease significantly.This study provides a new idea for the design of catalysts and reaction systems for efficient conversion of CO2.
The principle of adsorption and removal of benzene series by zeolite molecular sieves was described,and the methods,which including zeolite molecular sieve structure optimization,weakening hydrophilicity,cation compensation,pore multi-polarization,composite molecular sieve and so on,to improve the adsorption and removal performance of zeolite molecular sieves were discussed.When the flow rate is large and the pressure drop is high,the molecular sieve runner adsorption technology has high adsorption and removal efficiency for benzene series,and this technology is widely used in the industrial field.In addition,the problems to be solved in the adsorption and removal of benzene series by zeolite molecular sieves are improving hydrophobicity,stability and selectivity.
A primary hydrothermal method was used to adjust the thickness of Bi2O2CO3 nanosheets by adjusting the solvent,and construct hydrangea-like Bi2O2CO3 with different specific surface areas,func-tional group grafting and oxygen vacancies to improve the separation efficiency of photoexcited charge car-riers.The structures and topography were characterized by XRD,SEM,TEM and XPS.The photocatalytic properties of catalysts in tetracycline hydrochloride solution(TC),methyl orange solution(MO)and bis-phenol A solution(BPA)were studied by adsorption and degradation experiments.The results showed that the adsorption efficiency of MO,TC and BPA of the modified Bi2O2CO3 with ultra-thin structure(BiC-G)reached 81.1％,60.5％and 25.4％within 10 minutes,which were 2.32,5.5 and 3.18 times of the unmodified samples(BiC-W).After irradiation,the degradation efficiency was 86.3％,82.6％and 49.9％,which were 2.12,4.86 and 1.96 times of BiC-W.The above experimental results show that the modified catalyst provides more adsorption sites due to the grafting of functional groups and the generation of oxygen vacancies,which is the main reason for the improvement of photocatalytic performance.
A series of Mo-Bi catalysts were prepared by a microwave-assisted hydrothermal method for the oxidation reaction of isobutene(IB)to methacrolein(MAL).The catalysts were characterized by XRD,Raman,SEM and H2-TPR methods to determine Co6Fe4Mo12Bi1.5Ox,CoMoO4,MoO3 and FeMoO4 crystal-line phases.The researches focus on the effects of preparation time and temperature on catalysis perform-ance.Results showed that the catalyst particle morphology and composition were greatly affected by the preparation time.With the extension of preparation time,the agglomeration of catalyst particles was inten-sified,and the nanoparticles were transformed into micron rod-like particles,and more Co6Fe4Mo12Bi1.5Ox was generated at the same time.In addition,the preparation temperature of 160 ℃ was the most favorable for the formation of active phase.At the temperature,the catalysts prepared for 90 min and 120 min showed good catalytic performance,and the conversion of IB and the selectivity of MAL were both more than 90％.
A series of solid catalysts(HPWx/SMH-SiO2)with different HPW amounts were prepared by incipient impregnation method using submicron hollow silicon dioxide(SMH-SiO2)prepared by hard template method as support and phosphotungstic acid(HPW)as active component.The catalysts were systematically analyzed by infrared spectroscopy,ultraviolet spectrophotometry,X-ray diffraction,scanning electron microscopy,transmission electron microscopy and energy spectrum elements.The results show that HPW is successfully loaded into the hollow structure of SMH-SiO2,and HPW/SMH-SiO2 structure is complete with high thermal stability,chemical stability,catalytic activity in one-step synthesis adipic acid from hydrogen peroxide oxidation with cyclohexene.The catalyst is easy to be separated and recycled.
;The hydrogenation of coal tar to produce clean oil is an effective method to realize efficient con-version of coal tar.With the continuous improvement of fuel oil standard in our country,denitrification and desulfurization of coal tar has become a research hotspot.In this paper,the properties of coal tar and the hydrogenation process of coal tar are introduced,the research status of catalysts for hydrogenation of coal tar is reviewed,and the research direction of catalysts for hydrogenation of coal tar is prospected.It is pointed out that the development of new green-friendly hydrogenation catalyst is the key to realize the coal tar hydrogenation technology.
Volatile organic compounds（VOCs） are toxic organic compounds that threaten the environment and human health.Catalytic oxidation method is considered to be one of the most effective VOCs elimination methods because of its high efficiency, environmental protection and high removal rate.The supported bimetallic catalyst is applied to the removal of volatile organic compounds due to its good catalytic performance.In this paper, the catalytic performance of bi-noble metal, bi-non-noble metal and mixed metal catalysts for VOCs in recent years was reviewed.The influence of typical catalysts on VOCs oxidation was analyzed, and the future development trend of VOCs catalytic oxidation was prospected.
游离酶价格昂贵,活性不稳定,在高温、强酸和强碱条件下易失活.纳米模拟酶性能稳定,成本低,具有类酶活性.通过同步还原法制备一种具有类过氧化氢酶活性的纳米模拟酶(Cu-rGO),并负载磁性纳米粒子,制备磁性纳米模拟酶(Cu-rGO-Fe3O4),进行谱学表征以及条件优化,最后用于H2O2的分解.
近年来,乙醇汽油全面推广导致甲基叔丁基醚(MTBE)的应用受限,作为其原料之一的异丁烯需要另寻出路.异丁烯主要来源于催化裂化和蒸气裂解所产生的混合C4馏分,其通过选择性二聚反应可以生产高辛烷值的汽油添加剂.以Ni为助剂对HZSM-5进行改性,考察不同Ni负载量对催化性能的影响,并对一系列催化剂进行相关表征.结果表明,当Ni负载质量分数为0.25％时,综合效果最好,C8=收率为45.4％.表征结果表明,HZSM-5经Ni改性后,强酸位点的Lewis酸(L酸)和Brönsted酸(B酸)比值增加,对提高产物C8=选择性具有重要作用,该L酸中心可能来源于Ni物种与HZSM-5中的铝相互作用所生成的NiAl2O4.
ZSM-5分子筛作为工业上应用较广泛的催化剂之一,一直是研究的热点.但传统的ZSM-5分子筛存在晶粒大、扩散困难和活性位点可及性差的问题,限制了在大分子催化方面的应用.对近年来通过调节凝胶化学因素和合成条件因素来改善分子筛扩散困难问题的方法和机理进行综述,并指出利用长链季铵盐作为结构导向剂能够合成具有自柱撑形貌的ZSM-5分子筛,具有良好的晶间介孔连通性,但其制备过程繁琐,成本昂贵.尿素和晶种等添加剂的引入以及二段晶化法的成功应用使得合成的成本降低,改善了晶间介孔,使得ZSM-5分子筛具有更好的扩散性能.
催化化学(Catalytic Chemistry)是化学工业的基石,催化技术的发展和高效催化剂的创制对国民经济发展和社会进步起着重要的推动作用.传统化学工业在为人类提供所需物质的同时,普遍存在副产物多、资源浪费和环境污染等问题.绿色化学(Green Chemistry)是20世纪末崛起的一门新兴学科,是未来化学化工发展的主要方向.
以Al2O3为载体,采用共浸渍法制备Pd-Cu/Al2O3和Pd-Cu-N/Al2O3催化剂.利用连续流动微反应装置考察氮掺杂对Pd-Cu/Al2O3催化剂低温富氢气氛下CO优先氧化性能的影响,结合XRD、FT-IR、H2-TPR和XPS等手段对催化剂进行表征.结果表明,相较于Pd-Cu/Al2O3,Pd-Cu-N/Al2O3具有更好的CO优先氧化性能.氮掺杂促进了表面Cu2Cl(OH)3的分散,增强了Pd和Cu之间的相互作用,提高了 Pd和Cu2Cl(OH)3的氧化还原能力.同时,氮掺杂也有利于生成更多的表面活性Cu+物种,并且部分进入Pd晶格,抑制了反应过程中PdHx的形成,从而使催化剂催化性能提高.
为了提高Pt在TiO2上的分散,进一步提高Pt/TiO2催化氧化甲醛活性,采用超临界流体沉积(SCFD)方法制备Pt/TiO2,并对沉积工艺条件进行探索.对比不同催化剂Pt/TiNT和Pt/P25的催化活性,并采用TEM、N2吸附-脱附、TPR和XPS等对两种催化剂进行表征.结果表明,采用共溶剂(V乙醇∶V乙二醇=1∶1)、沉积时间1 h、沉积温度70℃及质量分数0.4％的Pt负载量时,催化剂的催化性能较佳,室温条件下甲醛在Pt/TiNT和Pt/P25上均发生了完全催化氧化反应,Pt/TiNT使甲醛在16 h内净化了 82.4％(降解率近100％),Pt/P25使甲醛净化了 52.4％(降解率70.3％).表征结果表明,TiNT管状阵列结构在SCFD中更有利于活性组分的有效分散,Pt和TiNT之间具有更强的相互作用,催化剂表面具有更多的负电荷和氧空位,因而表现出更高的催化活性.
以钴卟啉/N-羟基邻苯二甲酰亚胺(NHPI)为催化剂,分子氧为氧化剂,在无溶剂的条件下,研究温和条件下催化甲苯选择性氧化制备苯甲醛的工艺.在甲苯0.2 mol、钴卟啉物质的量分数1 ×10-4％、NHPI物质的量分数0.25％、70℃、O2压力2.0 MPa和3 h优化条件下,甲苯转化率为5.5％,苯甲醛、苯甲醇和苯甲酸选择性分别为88.0％、10.2％和0.8％.通过原位红外和电子顺磁共振波谱仪等表征方法,表明该反应机理为典型的自由基反应过程.
