一种新型固体酸的制备及其在二（1-萘）甲烷加氢裂解中的催化性能

煤直接液化制取轻质燃料油和重要化学品是实现煤炭资源高效洁净利用的有效途径。煤液化的关键是在适当的温度、氢压、溶剂和催化剂存在的条件下,通过加氢裂解反应使连接煤中有机质大分子结构单元的较弱的桥键断裂生成可作为液体燃料的有机小分子,经后续的精细分离得到高附加值有机化学品和制备高性能炭材料前驱体,进而实现煤炭资源的高效利用。传统的煤液化工艺反应条件苛刻,需要高温和高氢压,导致能耗大和设备成本较高。酸性催化剂可使煤结构中的桥键在远低于煤热解反应的温度下断裂,并可有效除去煤中的杂原子,大幅提高液化油收率,因此酸性催化剂得到许多研究者关注。液体酸,如三氟甲磺酸、氟硼酸以及金属卤化物熔盐等均相酸性催化剂是煤液化工艺中常用的催化剂。虽然这些催化剂具有催化效率高和不易失活等优点,但大多数均相催化剂难以回收和再生,生产成本高,设备腐蚀性大,环境污染严重,因此在实际应用中受到限制。固体酸是具有广泛工业应用前景的环境友好催化剂,因而对固体酸的研究具有重要意义。本研究将液体三氟甲磺酸(TFMSA)通过浸渍吸附法负载到酸化的凹凸棒土(ATA)上制备了一种新型固体酸催化剂 TFMSA/ATA,并在相同条件下制备了 TFMSA/g-Al2O3和 TFMSA/ZSM-5作为对比。对TFMSA/ATA进行了透射电镜、傅里叶变换红外光谱、X射线光电子能谱、X射线衍射、N2吸附以及 NH3程序升温脱附表征。结果表明, TFMSA有效负载于 ATA载体表面及孔隙中,未发现明显的团聚,载体与活性组分之间存在较强的相互作用;另外, TFMSA/ATA上出现超强酸位点,说明 TFMSA/ATA具有超强酸性。以二(1-萘)甲烷加氢裂解作为探针反应考察了 TFMSA/ATA对 Car–Calk桥键断裂的催化活性。结果表明,二(1-萘)甲烷在 N2气氛和甲醇溶剂中选择性地加氢裂解,仅得到萘和1-甲基萘,未检测到加氢产物,且产物萘的收率明显高于1-甲基萘的收率,说明 TFMSA/ATA对二(1-萘)甲烷选择性加氢裂解和由此产生的1-甲基萘脱甲基反应有显著的促进作用。在相同反应条件下, TFMSA/ATA的活性明显高于 TFMSA/g-Al2O3和 TFMSA/ZSM-5,这是由于 TFMSA/ATA较大的比表面积以及载体 ATA与活性组分 TFMSA之间存在较强的相互作用有利于催化剂释放质子。由催化剂释放的质子优先进攻二(1-萘)甲烷中的取代位导致 Car–Calk键断裂是二(1-萘)甲烷加氢裂解的关键步骤。催化剂循环实验表明, TFMSA/ATA在循环使用4次后仍具有较高的催化活性,使用后催化剂酸性没有明显降低,说明 TFMSA/ATA具有良好的稳定性。     

Effect of Catalyst Properties on Hydrocracking of Pyrolytic Lignin to Liquid Fuel in Supercritical Ethanol

The metal-acid bifunctional catalysts have been used for bio-oil upgrading and pyrolytic lignin hydrocracking. In this work, the effects of the metal-acid bifunctional catalyst properties, including acidity, pore size and supported metal on hydrocracking of pyrolytic lignin in supercritical ethanol and hydrogen were investigated at 260 ^oC. A series of catalysts were prepared and characterized by BET, XRD, and NH₃-TPD techniques. The results showed that enhancing the acidity of the catalyst without metal can promote pyrolytic lignin polymerization to form more solid and condensation to produce more water. The pore size of microporous catalyst was smaller than mesoporous catalyst. Together with strong acidity, it caused pyrolytic lignin further hydrocrack to numerous gas. Introducing Ru into acidic catalysts promoted pyrolytic lignin hydrocracking and inhibited the polymerization and condensation, which caused the yield of pyrolytic lignin liquefaction product to increase significantly. Therefore, bifunctional catalyst with high hydrocracking activity metal Ru supported on materials with acidic sites and mesopores was imperative to get satisfactory results for the conversion of pyrolytic lignin to liquid products under supercritical conditions and hydrogen atmosphere.     

Inside Cover: Mechanistic Understanding of Efficient Polyethylene Hydrocracking over Two-Dimensional Platinum-Anchored Tungsten Trioxide (Angew. Chem. Int. Ed. 40/2023)

Chemical upcycling of polyethylene (PE) can convert plastic waste into valuable resources. However, engineering a catalyst that allows PE decomposition at low temperatures with high activity remains a significant challenge. Herein, we anchored 0.2 wt.% platinum (Pt) on defective two-dimensional tungsten trioxide (2D WO₃) nanosheets and achieved hydrocracking of high-density polyethylene (HDPE) waste at 200–250 °C with a liquid fuel (C_5–18) formation rate up to 1456 g_products ⋅ g_{metal species}⁻¹ ⋅ h⁻¹. The reaction pathway over the bifunctional 2D Pt/WO₃ is elucidated by quasi-operando transmission infrared spectroscopy, where (I) well-dispersed Pt immobilized on 2D WO₃ nanosheets trigger the dissociation of hydrogen; (II) adsorption of PE and activation of C−C cleavage on WO₃ are through the formation of C=O/C=C intermediates; (III) intermediates are converted to alkane products by the dissociated H. Our study directly illustrates the synergistic role of bifunctional Pt/WO₃ catalyst in the hydrocracking of HDPE, paving the way for the development of high-performance catalysts with optimized chemical and morphological properties.     

催化剂的性质对超临界乙醇条件下热解木质素液化的影响

研究了在超临界乙醇中、氢气存在下,一系列金属-酸双功能催化剂的酸性、孔径大小、负载的金属对热解木质素加氢裂解过程的影响．制备并采用N₂等温吸附和BET比表面、X射线衍射、NH₃-程序升温脱附技术对催化剂进行表征．实验结果表明催化剂酸性增强可促进热解木质素的缩聚反应,从而产生大量的焦炭和水,导致其液化效率降低．微孔催化剂比介孔催化剂孔径小,与强酸共同作用会导致热解木质素裂解生成更多的小分子气体．在催化剂上负载金属Ru可有效地抑制热解木质素的缩聚反应,促进其裂解液化．     

Ni/MgO-Al2O3催化剂上高温焦油组分的催化转化

采用分步浸渍法制备了MgO-Al2O3负载的Ni基催化剂, 并运用N2吸附、载射线衍射(XRD)、透射电子显微镜(TEM)等手段进行表征. 该催化剂用于甲苯或萘为焦油模拟化合物的高温焦炉煤气(COG)的常压加氢裂解反应, 并考察了H2浓度、H2S对催化剂活性的影响. 结果表明: 催化剂还原后, 表面形成均匀分散、直径为8-14 nm的金属Ni纳米颗粒; 在较低的水碳摩尔比(nH2O/nC=0.28)时, 甲苯就能完全转化并选择性地加氢裂解形成CH4, 测试的时间内(480 min), 催化剂没有明显的失活和积炭现象, 显示出好的反应活性、稳定性和耐硫能力. 制得的Ni/MgO-Al2O3催化剂有望应用于较低水含量(10%-15%(φ, 体积分数))的高温焦炉煤气中焦油的直接转化.     

ICP-AES法同时测定加氢裂化催化剂中的Fe、Ni、Cu、V和Pb

用电感耦合等离子体发射光谱 (ICP- AES)法同时测定加氢裂化催化剂中 Fe、Ni、Cu、V、Pb的含量 ,以氢氟酸 -盐酸处理样品 ,优选了分析线和积分时间。此 5种被测元素回收率在 95 %— 10 5 %之间 ,相对标准偏差 <6 %,各元素的检出限依次为 :0 .0 0 0 5、0 .0 0 2、0 .0 14、0 .0 0 0 5、0 .0 0 2 9μg/ m L。     

镜煤吡啶不溶物及其热解加氢产物的NMR研究

本文对镜煤吡啶不溶物、热解加氢后吡啶及四氢呋喃不溶物进行了固体NMR研究,获得了12种结构参数,并对热解加氢产物中的苯可溶各馏份进行了一维、二维液体NMR研究,归属了其¹³C和¹H谱,计算了各馏份的平均分子结构.     

四氢萘在Mo-Ni/USY双功能催化剂上加氢裂化反应动力学的研究

在活性趋于稳定的Mo-Ni／USY双功能催化剂上，利用连续流动微反－色谱装置，进行了四氢萘加氢裂化反应动力学的研究，在320－400℃、4．5－8．5MPa反应条件下，考察其反应产物分布，建立了四氢萘加氢裂化反应动力模型，计算了反应网络中各步的反应速率常数和活化能，并讨论了反应网络的主线和反应条件对主线的影响。结果表明，Mo-Ni／USY双功能催化剂具有较高的裂化和异构化活性，低温、高压有利于加氢、高温、低压有利于裂化和异构。     

Catalytic coprocessing of waste plastics and petroleum residue into liquid fuel oils

Waste plastics of different types were catalytically coprocessed with petroleum residue of light Arabian crude oil in the presence of a number of catalysts. The purpose of the study was to explore effects of various conditions such as catalyst type, amount of catalyst, reaction time, pressure and temperature on the product distribution. The waste plastic studied included low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS) and polypropylene (PP). A series of single (waster plastic with catalyst) and binary (waste plastic and residue with catalyst) reactions were carried out in an autoclave reactor under variable reaction conditions. The reaction conditions used were 1, 3 and 5 wt.% catalysts, 30–120 min reaction time, 400–430 °C reaction temperature and 500–1200 psi hydrogen pressure. The product distribution achieved for residue/plastic/catalyst system showed higher yields of liquid fuels as compared to residue/plastic system. Hydrocarbon gases were formed as well along with heavy oils, insoluble gums and coke. At the reaction conditions of 3 wt.% NiMo catalyst, 90 min reaction time, 1200 psi hydrogen gas pressure, 430 °C temperature and residue to plastic feed ratio of 3:2 (wt.) afforded maximum conversion of the plastics into liquid fuel oils.     

Cs取代对Ni-H3PW12O40/SiO2催化剂结构性质和催化性能的影响

采用两步浸渍法和载体上的原位反应制备了一系列Cs部分取代的Ni-Cs_xH_3-xPW₁₂O₄₀/SiO₂催化剂,并用N₂吸附比表面积测定(BET)、电感耦合等离子体发射光谱(ICP)、X射线衍射(XRD)、拉曼光谱(Raman)、原位X射线衍射(in situ XRD)、NH₃程序升温脱附(NH₃-TPD)、H₂程序升温还原(H₂-TPR)、H₂程序升温脱附(H₂-TPD)、吡啶吸附傅里叶变换红外(FTIR)光谱等分析测试技术对催化剂进行了表征. 以正癸烷为模型化合物,对催化剂的加氢裂化性能进行了评价. 结果表明,8%Ni-50%Cs_1.5H_1.5PW/SiO₂催化剂具有最高的C₅₊收率,明显优于8%Ni-50%H₃PW/SiO₂催化剂和工业催化剂. 随着Cs 在Cs_xH_3-xPW中比例的增加,正癸烷的转化率逐渐降低,而C₅₊选择性则逐渐提高. 当催化剂具有合适的孔径时,选择性的提高是由于催化剂酸性的减弱,而转化率的降低则是由于催化剂加氢能力的减弱.