分子筛类型对正戊烷催化裂解反应性能的影响

为了解决石脑油中正戊烷难以高效催化裂解为低碳烯烃的问题,先采用Aspen Plus模拟软件对正戊烷的催化裂解反应进行热力学平衡分析,然后考察分子筛类型对正戊烷催化裂解的低碳烯烃收率和选择性的影响规律。对正戊烷的催化裂解反应进行热力学分析的结果表明,当反应温度高于650 ℃时,丙烯和乙烯的质量比m(C₃H₆)/m(C₂H₄)<1,且低碳烯烃(C₂H₄+C₃H₆+C₄H₈)的收率开始增速缓慢。因此,综合考虑m(C₃H₆)/m(C₂H₄)和低碳烯烃收率,选择在反应温度650 ℃下考察正戊烷在不同类型分子筛上的催化裂解反应性能。结果表明：在MTT分子筛上催化裂解的低碳烯烃选择性较高,在温度为650 ℃、压力为0.1MPa、MHSV为540 h^-1的反应条件下,正戊烷在MTT分子筛上催化裂解的低碳烯烃(C₂H₄+C₃H₆+C₄H₈)选择性为55.21%。通过对催化裂解过程的裂解和氢转移反应的分析,表明小孔径的MTT分子筛能够抑制双分子反应,包括双分子裂解反应和双分子氢转移反应,从而提高低碳烯烃的选择性。     

Pd和甲醛对Ag/C催化四氯化碳原位液相加氢脱氯性能的影响

采用100 mL反应釜,在N₂存在条件下,研究了Ag/C催化剂催化CCl₄液相原位加氢脱氯反应,考察了助催化剂Pd以及助剂甲醛溶液对CCl₄原位催化转化反应转化率和产物选择性的影响,并结合XRD、XPS表征技术分析了甲醛自身分解反应。结果表明,助催化剂Pd可以提高Ag/C催化剂的活性,以n(Pd)/n(Ag)为0.03的Pd-Ag/C催化剂的活性最高;但对产物CH₂Cl₂和CHCl₃的选择性没有影响,二者选择性之比仍维持在6/4。甲醛的加入明显提高Ag/C催化剂上CCl₄的转化率,同时也改变了产物分布;反应4 h,CCl₄转化率和CH₂Cl₂选择性均达到90%。甲醛主要起促进Ag/C催化剂表面Ag-Cl物种还原为Ag的作用。     

分子筛对甲醇制轻烯烃反应烃类产物选择性的影响

采用XRD、SEM、XRF、BET、NH₃-TPD等方法表征USY、Beta、ZSM-5、ZSM-22、SAPO-41和SAPO-34分子筛的物相、组成、结构和酸性,并采用脉冲微反技术考察这些分子筛催化甲醇转化反应活性及烃类产物选择性随反应温度的变化。结果表明,三维十二元环的USY和Beta分子筛的甲醇转化催化活性最高,其次为二维十元环的ZSM-5分子筛,一维十元环的ZSM-22分子筛最低。分子筛的孔结构与孔径尺寸具有择形效应,与反应温度共同影响高选择性烃类产物的碳链长度。大孔分子筛在反应温度450℃以下时的C₄ 烃选择性最高;在反应温度400℃以上时,中孔ZSM-5、ZSM-22和SAPO-41分子筛的C₃烃选择性最佳,小孔SAPO-34分子筛的C₃烃和C₂烃选择性最高。随着反应温度升高,高选择性烃产物的碳数降低。ZSM-5和SAPO-34分子筛是特别适合于甲醇制丙烯和乙烯的择形催化剂,这2种分子筛在催化选择性方面还具有优异的升温特性,在400~550℃范围,随着反应温度升高,产物中乙烯和丙烯的总选择性提高,副产物中丙烷、C₄、C₅和C₆₊烃的选择性降低,甲烷选择性略有增加。     

苏州大学的CO2加氢制甲醇Cu单原子催化剂研究获进展

近日,苏州大学的研究团队开发C₃N₄负载的Cu单原子催化剂,具有定制配位结构,即Cu-N₄和Cu-N₃,可作为低温CO₂加氢制甲醇的高选择性和高活性催化剂。相关研究成果发表于《自然·通讯》杂志。工业上通过提高温度或压力促进CO₂加氢制甲醇反应,由于CO₂的化学惰性和加氢过程复杂,导致催化剂活性与产物选择性较低。将Cu位点与金属氧化物(如ZnO,ZrO₂,TiO₂)复合的催化剂可用于CO₂加氢,但该类催化剂活性和甲醇选择性低、机制不明确,开发高效CO₂加氢制甲醇催化剂则具有重要意义。     

C4烯烃转化制丙烯工艺及催化剂研究

目的 开发C₄烯烃催化裂解制丙烯工艺和催化剂制备工艺技术,完成小试和工业侧线试验。方法 采用固定床评价装置考查了催化剂配方、改性及工业条件对催化剂活性、选择性、稳定性能的影响。结果 以ZSM-5分子筛为活性组分的催化剂在C₄烯烃转化制丙烯反应中具有较好的活性、选择性、稳定性和再生性,磷的引入未改变催化剂的晶型结构,但降低了催化剂酸性位点数量,并调节了催化剂的n(B酸)/n(L酸),随着磷负载量增加到5%(w),分子筛中磷与铝的相互作用逐渐增强,磷可以和骨架铝和非骨架铝相互作用。结论 C₄烯烃的转化率达到80%以上,丙烯的选择性达到35%～45%,催化剂的单程寿命达到一个月以上,且经再生后,再生恢复率达95%。     

氧气氧化环己烷合成环己酮的高效催化体系

通过筛选一系列催化剂和助催化剂,构建了氧气氧化环己烷合成环己酮的高效催化体系。考察了溶剂和反应条件对环己烷转化率和环己酮选择性的影响。采用气相色谱 (GC)对产物进行定量分析,采用色质联用(GC-MS)对反应途径和催化剂失活机理进行探讨。结果表明,以N-羟基邻苯二甲酰亚胺(NHPI）为催化剂,以Co(OAc)₂、Cr(OAc)₃和AlCl₃为助催化剂,以乙腈为溶剂,可以高效地催化氧气氧化环己烷反应。当n(NHPI)∶n(Co(OAc)₂)∶n(Cr(OAc)₃)∶n(AlCl₃)=10∶3∶1∶1,n(NHPI)∶n(CH₃CN)∶n(C₆H₁₂)=1∶20∶10,氧气压力1.0 MPa,于75℃反应6 h时,环己烷的转化率为54.4%,环己酮选择性为93.2%,环己醇选择性为4.9%。己二酸为主要的副产物,氧化过程生成的水是造成催化剂失活的主要原因。     

负载型MoO3/SiO2催化碳酸二甲酯和乙酸苯酯合成碳酸二苯酯

采用溶胶 凝胶法制备用于碳酸二甲酯(DMC)和乙酸苯酯(PA)合成碳酸二苯酯(DPC)的MoO₃/SiO₂催化剂,并对其进行N₂吸附-脱附、XRD表征。考察焙烧温度、MoO₃负载量以及反应条件等对该催化剂在DMC和PA酯交换反应中催化性能的影响。结果表明,焙烧温度为500℃、MoO₃负载量（m(MoO₃)/m(MoO₃+SiO₂)）为0.20时,制备得到的MoO₃/SiO₂催化剂在DMC和PA酯交换反应中的催化性能最优,在适宜的反应条件(m(Catalyst)=6.0 g, n (PA)=1.0 mol, n (PA) /n (DMC)=2, T=180℃, t=5 h)下,DMC转化率达71.1%,甲基苯基碳酸酯(MPC)及DPC的选择性分别为52.0%和43.5%。随着MoO₃负载量的增加,MoO₃/SiO₂催化剂比表面积降低,但催化性能却逐渐变好;载体SiO₂为无定形,活性组分MoO₃的(021)、(110)、(040)晶面取向随负载量的增加而发生改变,因此,催化剂的催化性能与活性组分MoO3的晶面取向和载体与活性组分间的协同作用有着一定的关系,择优取向晶面(021)、(110)更有利于DMC和PA合成DPC反应。     

铈源及其组成对乙苯脱氢制苯乙烯催化剂结构和性能的影响

以Ce(NO₃)₃和CeO₂为混合铈源制备了一系列Fe-K-Ce-Mo乙苯脱氢催化剂,并采用BET、XRD、CO₂ -TPD和XPS等手段对其进行表征,考察了m(Ce(NO₃)₃)/m(Ce(NO₃)₃+CeO₂)对该催化剂结构、酸碱性以及催化乙苯脱氢反应性能的影响。结果表明,m(Ce(NO₃)₃)/m(Ce(NO₃)₃+CeO₂)=0.60时,催化剂具有中等水平的比表面积、较低的孔体积和较大的孔径,产生较多的活性相,酸碱中心数目和强度达到最佳,晶格氧丰富,催化剂催化乙苯脱氢反应活性最佳。     

碳四炔烃选择性加氢催化剂研究进展

对碳四(C₄)馏分中的炔烃进行选择性催化加氢是实现混合C₄资源高附加值利用的有效途径,具有显著的经济效益和社会效益。通过介绍C₄炔烃的利用现状,并从选择性加氢机理入手,对国内外现有C₄炔烃催化剂的研究与应用进行了概述;对非贵金属镍(Ni)、铜(Cu)催化剂与贵金属钯(Pd)催化剂的优缺点进行了对比,指出了Pd系列催化剂是目前最适合作为C₄炔烃选择加氢的催化剂。针对Pd系催化剂目前存在的不足,提出了一些改进策略与今后的研究方向。分析研究表明,Pd系纳米催化剂的载体预处理、助剂改性、微观调控以及单原子催化剂的可控制备是国内C₄资源充分利用的重要途径。     

SO3H-MCM-41对丙烯酸和异丁烯加成反应的催化性能

采用一步水热共缩合法制备了表面磺酸嫁接的介孔分子筛SO₃H-MCM-41,采用XRD、N₂吸附-脱附、红外吸收光谱、吡啶吸附红外光谱、酸碱滴定等手段对其物理化学性质进行了表征,考察了SO₃H-MCM-41对丙烯酸与异丁烯直接加成反应合成丙烯酸叔丁酯的催化性能,在n(#em/em#-Butene)/n(Acrylic acid) =1时,探讨了催化剂制备条件n(Sulfonic acid)/n(Silica) ,丙烯酸与异丁烯加成反应条件m(t-Butanol)/m(Acrylic acid)、m(Catalyst)/m(Acrylic acid)和反应温度对反应转化率及产物选择性的影响。结果表明,SO₃H-MCM-41表面成功嫁接了磺酸基团,嫁接后的分子筛具有纯硅MCM-41分子筛的晶体结构。提高n(#em/em#-Butene)/n(Acrylic acid)可以显著提高丙烯酸转化率,而丙烯酸叔丁酯选择性基本保持不变;采用n(Sulfonic acid)/n(Silica)=0.3制备的SO₃H-MCM-41催化剂,在反应时间6 h、反应温度50℃、n(#em/em#-Butene)/n(Acrylic acid)=2、m(Catalyst)/m(Acrylic acid)=0.01和m(t-Butanol)/m(Acrylic acid)=0.04的条件下,丙烯酸转化率为90.0%,丙烯酸叔丁酯选择性为92.8%,二异丁烯选择性为4.8%。SO₃H-MCM-41催化剂重复使用5次其催化活性保持稳定。在工业生产过程中,提高丙烯酸转化率有利于降低丙烯酸与丙烯酸叔丁酯的分离能耗。     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^-1, and n(H₂):n(CO) = 2.0 in feed.     

碱土及锰系复合氧化物担载Fe-K催化剂的费-托合成性能

制备了铝氧化物(Al-O)基体分别与Mn或碱土元素构成的复合氧化物型高温钝化系列载体,担载Fe-K后制成Fe-K₂O/MAl₂O₄ (M为Mg、Ca、Sr、Ba、Mn)催化剂,用于费-托合成反应。采用X射线粉末衍射(XRD)、电感耦合等离子体发射光谱(ICP-OES)、N₂物理吸附、CO₂化学吸附 程序升温脱附(CO₂-TPD)、场发射电子显微镜等分析方法表征了Fe-K₂O/MAl₂O₄催化剂的物理化学性质。采用固定床加压反应器进行了催化剂的合成气费-托转化催化性能评价。结果表明：不同元素种类(Mg、Ca、Sr、Ba、Mn)造成Fe-K₂O/MAl₂O₄催化剂的CO₂-TPD高温脱附峰面积占总脱附峰面积百分比、高温脱附峰温度等出现显著差异。对Fe-K₂O/MAl₂O₄催化剂来说,表面碱性位的碱性越强,则催化剂的活性越高。发现所制备的5种Fe-K₂O/MAl₂O₄催化剂的C₂~C₄烯/烷比、C-C偶合能力、低碳烯烃烃类选择性均与其CO₂-TPD高温脱附峰温度大致呈反向关系,即当CO₂-TPD高温脱附峰温度越高时,三者的数值将趋于越低。CO₂-TPD高温脱附峰温度位于669～692 ℃的Fe-K₂O/Mg Al₂O₄、Fe-K₂O/MAl₂O₄催化剂比位于744～749 ℃的Fe-K₂O/CaAl₂O₄、Fe-K₂O/Sr Al₂O₄、Fe-K₂O/BaAl₂O₄催化剂更有利于促使反应生成低碳烯烃。     

EFFECTS OF SUPPORTS ON THE ACTIVITY OF NICKEL CATALYST FOR CH4 REFORMING WITH CO2

Nickel catalyst is an effective catalyst for reforming CH₄ with CO₂. The reaction between CO₂ and CH₄ at 1073 K. in the pressure of 0·1 MPa has been studied over different materials supported nickel metal in a fixed-bed reactor. Different catalysts before and after reaction were characterized by SEM, XRD, XPS. Results shows that CO and H₂ are basically produced at the same ratio. When the feed ratio CO₂/CH₄ is less than 0·5, less C₂~C₄ hydrocarbons are detected. When the feed ratio CO₂/CH₄ is 1, Ni/a- Al₂O₃ catalyst has the highest activity. However, when the feed ratio CO₂/CH₄ is greater than 1, Ni/y- A1/O₃, Ni/a- A1₂O₃, Ni/SiO₂ and Ni/HZSM-5 had higher activity; Ni/clinoptilolite basically no activity. Different kinds of carbon deposit are established.     

TWO STAGE DIRECT COAL GASIFICATION TO C2-C4 HYDROCARBONS

Results of a study conducted to convert coal to C₂-C₄ hydrocarbons in a two-stage reactor system are presented. Coal was converted to liquids at 440° C in a stirred batch autoclave using tetralin as the hydrogen donor solvent. The liquids produced were separated from the unreacted coal and ash by filtration. The liquids were then fed into a second stage fixed bed reactor containing sulfided Ni-M0/AI₂O₃ and Si0₂-AbO;5 catalyst. The liquids were hydrocracked on the dual-functional catalyst giving high yields of C₂-C₄ hydrocarbons. The pressure was 1800 psig and the temperatures were in the range of 425 to 500° C. Reaction mechanisms of conversion of coal derived liquids to C₂-C₄ hydrocarbons are presented. The kinetic parameters of the conversion of coal liquids to gases were determined. The activation energy was determined to be 23.9 Kcal/mol Cracking reactions involving C-C bonds appear to be rate-controlling.     

连接链长度对交联聚苯乙烯固定N-羟基邻苯二甲酰亚胺催化环己基苯氧化的影响

为解决N-羟基邻苯二甲酰亚胺(NHPI)催化剂难以回收利用的问题,采用不同链长的卤代烃,通过烷基化反应,将NHPI化学固定于交联聚苯乙烯(CPS)微球,制得了具有不同长度连接链的CPS-NHPI-C_n非均相催化剂。采用X射线光电子能谱(XPS)、红外光谱(FT-IR)、N₂吸附-脱附(BET)、扫描电子显微镜(SEM)等分析手段进行表征。将所制备的CPS-NHPI-C_n用于催化环己基苯(CHB)氧化过程,考察了连接链长度(C₁~C₉)及反应条件对催化性能的影响。结果表明：连接链长度明显影响CPS-NHPI-C_n的催化性能,连接链长从度C₁增至C₆,CPS-NHPI-C_n催化剂的活性增加。以CPS-NHP-C₆为催化剂,在95 ℃、1 MPaO₂分压下反应8h,环己基苯的转化率为28.4%,环己酮和苯酚的选择性分别为90.7%和87.6%。CPS-NHP-C6循环使用10次,其催化性能没有明显下降。     

Ni/ZSM-5 CATALYST FOR CH4 REFORMING WITH CO2

For good physical and chemical proprieties of ZSM-5 and its selectivity to higher hydrocarbons it is selected as support carrier. In this paper CH₄ reforming with CO₂ to synthesize heavier hydrocarbons over Ni/ZSM-5 catalyst is investigated. The reforming reaction is operated at 1073K under the ambient pressure in a fixed-bed tabular reactor. As promoter rare earth oxides, La₂O₃, CeO₂, Pr₆O₁₁ and Nd₂O₃ are separately added to Ni/ZSM-5 and Ni-La/ZSM-5(NZL), Ni-Ce/ZSM-5(NZC), Ni-Pr/ZSM-5(NZP) and Ni-Nd/ZSM-5(NZN) are formed accordingly. For convenience, they are recorded as Ni-RE/ZSM-5. When these catalysts are used in the reforming reaction the yield of heavier hydrocarbons is obviously increased. The structure of Ni-RE/ZSM-5 catalysts before and after reaction is systematically characterized by XRD, XPS, TEM, SEM, ICP and FTIR. After 10 hours reaction there are more carbon deposit on Ni-RE/ZSM-5 catalyst than Ni/ZSM-5, but their structure are not destroyed and carbon deposit is easy gasified.     

顶空悬滴液相微萃取技术在油气化探中的应用

油气化探的理论基础是地下油气藏中的烃类向上渗漏,在近地表形成一系列可被检测的有规律的地球化学响应,而油气化探通常以C1-C5烃类为检测对象。如果说土壤或沉积物中的C1-C4烃类还有可能是细菌作用形成的,那么C6-C12的烃组分则应该完全为热成因的。因此,检测土壤或海底沉积物中的C6-C12的烃组分,可以为油气藏预测提供最直接的证据。由于汽油烃组分在土壤和海底沉积物中含量低及检测手段和技术的缺乏,导致汽油烃组分在油气化探中很少被关注。以分析完罐顶气后的钻井岩屑液体为对象,采用顶空悬滴液相微萃取技术(HS-SDME),对某钻井中不同深度的汽油烃(C6-C12)组分进行定量分析。研究结果显示,通过HS-SDME法可以很好地检测钻井岩屑液体中的汽油烃组分,且利用这些汽油烃组分含量判别的钻井油气储层深度与实际储层深度一致,表明HS-SDME法可用于井中化探及地表油气化探。     

土壤中分段石油烃热脱附行为研究

采用管式炉模拟土壤中石油烃热脱附过程,考察了加热温度、保持时间以及负压条件对土壤中分段石油烃热脱附过程的影响,为实际石油烃污染土壤修复工作提供理论依据.结果表明:提高加热温度、延长保持时间以及提供负压条件均对提高土壤中总石油烃去除率产生积极作用;常压下,在250℃保持2 h与300℃保持1 h的条件下,土壤中总石油烃去...     

THERMAL DECOMPOSITION OF SAUDI CRUDE OIL ASPHALTENES

Asphaltenes precipitated by the use of pentane, heptane and decane solvents from Saudi Arabian Light (AL) and Saudi Arabian Heavy (AH) crude oils 370^°C + residua have been investigated by thermal gravimetric analysis and pyrolysis - gas chromatographic analysis at 350^°C and 520^°C. Gas chromatographic analysis of the gases evolved during pyrolysis has shown that CO, CO₂ and CH₄ constitute the major portion of the gases evolved at 350^°C from pentane and heptane asphaltenes of AH residue and from pentane asphaltenes of AL residue. Whereas gases evolved from decane asphaltenes are dominated by CO₂ and C₂-C₄ hydrocarbon gases. At 520^°C, hydrogen and methane represent 56-80 vol %of the gases evolved from all the four asphaltenes. The amounts of C₁-C₄ hydrocarbon gases increased with an increase in the carbon number of the precipitating solvent at 350^°C and decreased at 520^°C. The presence of up to C₃₆ normal alkane hydrocarbon has been indicated in the maltenes produced from these asphaltenes. The loss of nitrogen from AH asphaltenes during pyrolysis remained low (1-6 wt %), whereas the losses of oxygen and sulphur ranged from 58 to 74 wt % and 10 to 29 wt %, respectively.