高温煤气中氨的脱除：Ⅱ.氨催化分解动力学的研究

研究了Ｎｉ－ ３催化剂分解氨的动力学。考察了各种反应条件如温度、空速以及气体中的氨和氢的浓度对反应的影响,确立了氨催化分解动力学方程式。当操作空速为３０００ｈ－ １ 时,在５８０ ～６３０℃的温度区间内,反应主要受化学反应控制;在６３０～７００℃的温度区间内,反应受扩散影响较为严重;在７００℃以上的温度区间内,反应在一定程度上受平衡的影响。随着空速的增大反应速率增大,但转化率却有所减小;气体中氨浓度的增大对反应转化率没有什么影响,氢浓度的增大使反应转化率明显减小。在５８０～６３０℃的温度范围内,空速３０００ｈ－ １ 的操作条件下动力学方程式如下：Ｒ＝ ３．４２３×１０１３ｅ－ ２７６ ．４５ ×１０３ＲＴ ＣＮＨ３·Ｃ－ １－５Ｈ２     

板状镍催化剂上氨分解和氨部分氧化制氮氢气的研究

研制了一种 Ni/Al₂O₃多孔板状催化剂.该催化剂在反应温度高于750℃,氨分解率高于99.5%时,允许反应空速达10000—40000h^-1.用该催化板组装的反应器可采用内加热形式,和一般的外加热反应器相比可节约能耗约30%.在催化板上氨分解的经验动力学方程是γ=kp²NH₃,表观活化能为153.0kJ/mol.将该催化剂用于氨部分氧化时,在空气和氨比为1.0—1.7,680—750℃,氨空速10000—40000h^-1条件下,在氨点火后无外加能源情况下,能制得含氢30～43%,残氧小于0.1%的氮氢混合气,氨的转化率>99.5%,连续250小时反应表明,催化剂活性稳定.宏观动力学研究得出,反应对氨呈零级,表观活化能为37.2kJ/mol.     

新体系氨合成催化剂母体中Fe1-xO的歧化及其效应

Ｆｅ１－ｘＯ基氨合成催化剂分别在室温和２５０℃下真空脱２ｈ和５ｈ后,再在真客和４００℃下进行６０ｈ的热处理,利用ＸＲＤ,ＴＧ和催化反应评价等方法研究了真空热处理过程中Ｆｅ１－ｘＯ的歧化行为及热处理对Ｆｅ１－ｘＯ基催化剂还原性能和催化活性的影响,结果表明,Ｆｅ１－ｘＯ基催化剂母体中的Ｆｅ１－ｘＯ在热处理过程中的歧化行为与助催化剂有关,助催化剂对Ｆｅ１－ｘＯ的歧化有一定的抑制作用,无助催化剂和单、双助     

助催化剂对Fe1-xO基氨合成催化剂还原性能的影响

当助催化剂存在是地,Ｆｅ１－ｘＯ基催化剂的还原性能明显优于Ｆｅ３Ｏ４基催化剂,其原因是铝、钾、钙的氧化物对催化剂母体相Ｆｅ１－ｘＯ和Ｆｅ３Ｏ４还原性能的影响不同。由于Ａｌ＾３＋大量地进入Ｆｅ３Ｏ４的晶格而强烈地阻止Ｆｅ３Ｏ４的还原,只有少量的Ａｌ＾３＋能进入Ｆｅ１－ｘＯ晶格,因此对Ｆｅ１－ｘＯ的还原影响很小;     

助催化剂对Fe1-xO基氨合成催化剂活性的影响研究

用高温熔融法制备了不同化学组成的氨合成铁基催化剂。利用催化反应评价、物理吸附技术、ＸＲＤ和Ｍｌｓｓｂａｕｅｒ谱技术研究了助催化剂对Ｆｅ１－ｘＯ基和Ｆｅ３Ｏ４基催化剂的活性、比表面积和孔结构的影响。     

高温煤气中氨的脱除：Ⅰ.氨催化分解催化剂的筛选

制备和筛选了１２ 种氨催化分解催化剂,所选催化剂包括Ｃｕ － Ｍｎ 基脱硫剂,Ｚｎ－ Ｔｉ 基脱硫剂,Ｆｅ 基催化剂及Ｎｉ 基催化剂四大类,其中Ｎｉ－２ 催化剂及Ｎｉ－ ３ 催化剂具有较高的转化率。然后对Ｎｉ－３ 催化剂进行了寿命试验,１００ｈ 内其活性基本维持不变;耐硫性实验表明Ｎｉ－３ 催化剂具有一定的耐硫性能,因而它是所选的最优催化剂     

Mn-Ce-O催化剂组成对氨超临界水氧化性能的影响

用共沉淀方法制备了锰铈摩尔比分别为10/0、8/2、6/4、5/5、4/6、2/8和0/10的七种Mn-Ce-O复合氧化物催化剂.在450 ℃、25 MPa、停留时间1 s和氧化剂量为化学计量2.94倍的条件下,利用连续超临界水氧化反应装置考察了催化剂组成与其催化氨降解性能的关系.结果表明,催化剂组成与其活性间有着强烈的相关性,锰铈摩尔比为5/5的催化剂表现出最高的活性,氨转化率达到99.7%.用低温N2吸附、X射线衍射以及程序升温还原等方法表征了催化剂比表面积、物相结构和氧化还原性能,揭示了Mn和Ce的氧化物之间存在协同作用.     

烯烃的催化不对称氨羟基化反应

烯烃的催化不对称氨羟基化反应是Ｓｈａｒｐｌｅｓｓ继手性钛络合物催化的烯丙醇的不对称环氧化反应和烯烃的催化不对称双羟基化反应这后发现的又一极为重要的催化不对称反应。本文对这一新反应作一综述。     

Self-assembled CuO nanoarchitectures and their catalytic activity in the thermal decomposition of ammonium perchlorate

CuO shuttle-like and flower-like nanocrystals were synthesized through a one-step, low-temperature solution-phase method in the presence of a cation surfactant, hexadecyl trimethyl ammonium bromide. These nanocrystals were studied as an additive for promoting the thermal decomposition of ammonium perchlorate (AP). With the addition of CuO shuttle-like and flower-like nanocrystals, the thermal decomposition temperature of AP decreased. The structure, particle size, and morphology of resulting CuO powders were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Thermogravimetric analysis technique was applied to investigate the thermal decomposition of mixtures of AP and as-prepared CuO nanocrystals.     

Synthese und Zerfall von Azoinitiatoren,I

Azoesters of the typePhR ¹R²CN=NCR ²R¹Ph(R ¹=alkyl,R ²=rest of carboxylic acids) were synthesized; their 10h-half-life-temperatures and energies of activation of the decomposition were determined. The decomposition of the azo compounds follows a law of first order. The variation of the substituentsR ¹ andR ² gives information about the effect on the decomposition of the azo compounds. The azoesters of acetic acid are outstanding by low temperatures of decomposition and are situated in the range of azoisobutyronitrile.

     

负载Fe3（CO）12催化剂的制备及合成氨的催化活性

以Ｆｅ_３（ＣＯ）_（１２）为母体,以活性氧化铝或活性炭为载体制备了负载型氨合成催化剂．在固定床管式流动反应系统中测定了催化活性,并与以Ｒｕ_３（ＣＯ）_（１２）和ＲｕＣｌ_３·ｘＨ_２Ｏ为母体的负载催化剂以及低温高活性氨合成工业催化剂的活性进行了对比。结果表明：以活性炭为载体的Ｆｅ_３（ＣＯ）_（１２）催化剂在１５ＭＰａ、４００℃以上表现出很高活性,且每克纯活性组分的催化活性在某些温度下比当前活性较高的工业熔铁催化剂的活性要高得多,但低温常压下几乎无活性。负载钉催化剂在低温常压下即显活性,且以ＲｕＣｌ_３·ｘＨ_２Ｏ为母体,比以Ｒｕ_３（ＣＯ）_（１２）为母体的负载钌催化剂活性高。     

富马酸福莫特罗的合成工艺研究

富马酸福莫特罗作为特效哮喘治疗药物被临床广泛应用,本文对其合成工艺进行了研究并对重要中间体的合成工艺进行了优化。以4-羟基-3-硝基-苯乙酮为原料,经苄基化、溴代、还原、环氧化四步反应得到重要中间体4-苄氧基-3-硝基苯基环氧乙烷(3)。在制备中间体3时,采用一锅法,简化了反应步骤,同时在反应中加入了缚酸剂碳酸钾,加快了反应速率并提高了收率。此外,以对甲氧基苯基丙酮为原料,经过还原胺化反应一步生成另一个重要中间体1-(4-甲氧基苯基-2-甲基乙基)苄胺(4)。中间体3和4经偶合生成化合物5,在制备5时,采用微波合成,大大缩短了反应时间。中间体5再经硝基还原、甲酰化、去保护、成盐得到富马酸福莫特罗。该工艺操作简单,适合工业化生产,总收率达7. 46%。     

以氨水做碱源胶态晶种导向法合成小晶粒TS-1分子筛

TS-1分子筛具有MFI拓扑结构,因其独特的择形选择性和优异的催化氧化能力而广受关注.最早报道的TS-1合成方法采用大量四丙基氢氧化铵(TPAOH)作为有机结构导向剂, TPAOH价格昂贵,制约着TS-1分子筛大规模应用.开发廉价、环境友好的合成工艺是TS-1分子筛合成领域的重要课题.以价格相对较低的四丙基溴化铵(TPABr)代替TPAOH做有机结构导向剂,以氨水为碱源可合成TS-1分子筛,但产物晶粒尺寸远远大于以TPAOH做模板的合成结果,影响TS-1分子筛的传质和催化性能.因此,人们对该法进行了改进,选用有机胺作为碱源, TPABr为结构导向剂合成TS-1分子筛,但始终未能将其晶粒尺寸降至1μm以下.在合成体系中引入预先合成的TS-1分子筛或TS-1胶态前驱体作为晶种可以促进成核,缩短成核诱导期,有利于获得小晶粒尺寸的TS-1分子筛.此类方法往往需要辅助以大量有机胺等结构导向剂;胶态TS-1前驱体的制备需要特别小心以保证晶种中Ti的四配位状态,通常需要经历低温水解钛酸四丁酯(TBOT)和高温加热除醇等繁琐步骤.而胶态纯硅silicalite-1制备则相对简单,且已广泛用于导向合成同样具有MFI结构的ZSM-5沸石,但目前鲜有以silicalite-1做晶种合成TS-1分子筛的报道.基于此,本文以纯硅胶态silicalite-1为晶种,以氨水做碱源,辅助以少量TPABr做导向剂,合成了小晶粒TS-1分子筛,并以正己烯环氧化和环己酮氨肟化做探针反应考察了所得TS-1分子筛的催化氧化性能. X射线衍射结果表明,当晶种中SiO2占合成体系中SiO2的10 wt%(晶种引入TPAOH, TPAOH/SiO2=0.35),加入TPABr (TPABr/SiO2=0.03)做辅助结构导向剂,即合成体系中总(TPAOH+TPABr)/SiO2摩尔比低至0.07时,所得样品依然具有良好的结晶度.扫描电镜照片观察不到无定形物存在;晶种中SiO2占合成体系中SiO2的10 wt%时,所得TS-1晶粒尺寸约为250 nm ×150 nm ×50 nm;其他条件不变,胶态晶种用量增加到15 wt%时,初级晶粒尺寸基本保持不变,晶粒-晶粒之间交叉生长,形成孪生形貌;继续增加胶态晶种用量至20 wt%时,晶粒尺寸下降至仅100 nm左右;而用20 wt%胶态晶种所含相同量的TPAOH来代替胶态晶种,得到样品呈近10μm的大块状.与之对应的是,胶态silicalite-1晶种导向得到的小晶粒TS-1分子筛具有比直接用TPAOH得到的大块状样品更大的外比表面积和堆积孔体积.分析结果显示所得TS-1分子筛的体相TiO2/SiO2比在41–43.红外光谱和紫外可见光谱结果表明,胶态晶种导向法所得TS-1分子筛中的Ti主要以四配位状态存在,而直接用TPAOH合成的大块状样品则呈现显著骨架外Ti吸收峰,说明胶态晶种有助于Ti物种进入分子筛骨架.在催化正己烯环氧化反应时,用胶态silicalite-1晶种导向得到的小晶粒TS-1分子筛表现出与大块状TS-1相似的催化性能;而以环己酮氨肟化做探针反应时,小晶粒TS-1分子筛因具有外比表面积大和扩散路径短等优点而表现出远远高于大块状TS-1分子筛的催化活性.但与文献报道的相同SiO2/TiO2比的TS-1分子筛比较,本文所得小晶粒TS-1分子筛催化正己烯环氧化的活性略差.提高该小晶粒TS-1分子筛正己烯环氧化活性和建立构-效关系是下一步工作的重点.     

Model-free kinetics analysis of decomposition of polypropylene over Al-MCM-41

Both thermal and catalytic decomposition of PP sample is studied to understand the effect of catalyst (Al-MCM-41) on the decomposition behaviour. Mesoporous catalyst (Al-MCM-41) is synthesized by sol–gel methods and characterized by X-ray diffraction (XRD) analysis and nitrogen adsorption study. The optimum catalyst composition is found to be around 18.5 wt%, where the reduction in maximum decomposition temperature is around 103 °C. The nonlinear Vyazovkin model-free technique is applied to evaluate the quantitative information on variation of E with for PP sample under both catalytic and noncatalytic nonisothermal conditions.

The constant pattern behaviour of the TG curves and the similar trend on variation of E with for both catalytic and noncatalytic decomposition of PP indicates similar mechanism involved during decomposition. The only effect of catalyst is observed in the form of reduction of the temperature and the activation energy. The literature reported data on such variation are compared with the results of the present study. Results show that Al-MCM-41 is superior to the ZSM-5 catalyst in terms of catalyst loading due to the existence of larger external macropore and mesopore surface in it.     

Decomposition of NH3 on Pd and Ir Comparison with Pt and Rh

The unimolecular decompositions of NH₃ on polycrystalline wires and foils of Pd and Ir are examined and compared with the corresponding ones on Pt and Rh. The reactions were carried out in a differential flow reactor, at pressures from 0.01 to 1 Torr and temperatures from 500 to 1900 K. It was found that the rates of product formation could be fit by Langmuir-Hinshelwood unimolecular rate expressions, with an accuracy of ±20% under all conditions. Ammonia decomposes to N₂ and the rate of decomposition is fastest on Ir by several orders of magnitude when compared with that on the other metals, becoming flux limited above about 750 K. Ir appears to be the choice catalyst for dehydrogenating ammonia. The heats of adsorption of NH₃ on Pt, Rh and Pd are similar and equal to 16.7, 16.8 and 17.4 kcal/mol, respectively. The apparent activation energy for this reaction is similar on Pt and Rh and equal to 21 kcal/mol, while for Pd and Ir it is 26.2 and 31.2 kcal/mol, respectively.     

Model-free kinetics analysis of ZSM-5 catalyzed pyrolysis of waste LDPE

Both thermal and catalytic decomposition of waste LDPE sample is studied to understand the effect of catalyst (ZSM-5) on the decomposition behaviour. The nonlinear Vyazovkin model-free technique is applied to evaluate the quantitative information on variation of E_α with α for waste LDPE sample under both catalytic and noncatalytic nonisothermal conditions. The literature reported data on such variation under noncatalytic condition and effects of different catalysts on the LDPE sample are compared with the results of the present study.Results show that the optimum catalyst composition is around 20 wt.%, where the reduction in maximum decomposition temperature is around 70 °C. Presence of ZSM-5 shows similar reduction in maximum decomposition temperature as reported for Al-MCM-41 and MCM-41. Similar trend to literature reported data is observed for variation of E_α with α for LDPE under nonisothermal noncatalytic condition. ZSM-5 catalyzed decomposition of the LDPE sample in the present study indicates that E_α is strong and increasing function of α and consists of four steps. Cracking of large polymer fragments on the external surface of the catalyst, oligomerization, cyclization, and hydrogen transfer reactions inside the catalyst pores might be the possible reaction mechanisms involved during catalytic decomposition.     

Optimized Synthesis of Vinyl Ether Sugars and Vinyl Glycosides through Transfer Vinylation Catalyzed by (4,7‐Ph2‐phen)Pd(OOCCF3)2

Sugar vinyl ethers and vinyl glycosides are conveniently synthesized by catalytic transfer vinylation with butyl vinyl ether, which serves as both the solvent and source of vinyl. The air‐stable catalyst (4,7‐diphenyl‐1,10‐phenanthroline)Pd(OOCCF₃)₂ is prepared in situ from commercially available components.     

Novel Ruthenium Catalyst (K-Ru/C_(60/70)) for Ammonia Synthesis

Commercialdoublyortriply-promotedfusedironcatalystshavebeenwidelyusedstilluptonow.Theindustrialammoniacatalyticprocessonpromotedironcatalystsunderhighpressureandathightemperaturehasnotundergoneessentialchangesuptothepresentday.Alkalimetal-promotedrutheniumwasfoundtobeanactivecatalystforammoniasynthesisunderatmosphericpressurein1970s.Rutheniumcatalystcanbeconsideredasasecond-generation-catalystforammoniasynthesisaftertheiron-basedcatalyst'-'.Recently,weinvestigatedactivityofammoniasynthesisofru…