由煤系高岭土合成小晶粒NaY分子筛及其应用

利用不同的方法分别合成了常规尺寸和纳米NaY分子筛,并采用XRD和TEM手段对合成样品进行了表征,小晶粒分子筛其粒径小于100 nm。催化裂化试验表明,纳米分子筛可提高大分子转化能力及改善产物选择性,比常规晶粒尺寸分子筛更为优越的性能。     

薄片状Y型分子筛的合成及其裂化性能

采用导向剂法,以聚乙二醇-600（PEG-600）为形貌控制剂和分散剂,制备了具有薄片状形貌的小晶粒Y型分子筛。通过X射线衍射（XRD）、扫描电镜（SEM）、N₂吸附-脱附、吸附吡啶的原位红外和NH₃程序升温脱附（NH₃-TPD）技术对合成的Y型分子筛及制备的催化剂进行了表征。结果表明,所合成的Y型分子筛大部分呈薄片状形貌,相对于传统八面体形貌Y型分子筛来说,具有较高的外比表面积。1,3,5-三异丙基苯的催化裂化反应结果表明,与传统八面体形貌的Y型分子筛制备的催化剂相比,薄片状Y型分子筛具有较高的1,3,5-三异丙基苯裂化活性和裂化产物选择性。     

Application of Novel Zeolite Y Nanoparticles in Catalytic Cracking Reactions

The cracking activity of a fluid catalytic cracking (FCC) catalyst containing novel zeolite Y nanoparticles fabricated using mesoporous silica (average particle size of 150 nm) was examined and compared with the performance of other catalysts. The activity experiments were carried out in a fluidized bench-scale batch riser simulator reactor. The bulky probing compound of 1,3,5-triisopropylbenzene (TIPB) was cracked to lighter compounds over a catalyst containing 25% of the developed zeolite. The synthesized sodium-type zeolite nanoparticles were subjected to two cycles of ion-exchange treatment using ammonium sulfate and lanthanum chloride and then to calcination. To investigate the effects of particle size on the activity, three additional catalysts were prepared with the mean particle size of the supported zeolites ranging from 450 to 1800 nm. The preparation of the FCC catalysts was conducted by mixing the highly aqueous dispersed zeolite Y nanoparticles with colloidal silica–alumina as a matrix and silica sol as a binder. The results of the catalytic cracking of TIPB demonstrated the significant effect of the size reduction of the synthesized zeolite Y nanoparticles on the catalytic performance of the catalyst. The FCC catalyst that contained zeolite Y nanoparticles (150 nm) showed superior conversion and selectivity percentages for the main products. The results of this study have a direct implication on the preparation of colloidal catalysts containing zeolite Y nanoparticles, which form stable emulsion with petroleum products. These emulsions can be utilized for slurry and ebullated bed reactors in heavy oil upgrading applications.     

Exhausted fluid catalytic cracking catalysts as raw materials for zeolite synthesis

The utilization of exhausted fluid catalytic cracking (FCC) catalysts as raw materials for the zeolite synthesis was analyzed. Samples of the catalysts directly released from FCC units and the corresponding impact grinding pretreated samples were used. Mechanical treatment was observed to decrease catalyst crystallinity and particle size. The catalyst reactivity was analyzed in terms of conversion in zeolite and product properties. Hydrothermal synthesis experiments in NaOH medium were performed. Catalysts conversion in A and X type zeolites was obtained for treated and not treated samples. In particular, high conversion in NaX type were achieved using the more siliceous catalyst, whereas grinding activation produces a decrease of particle size and Al/Si ratio of the zeolites obtained.     

催化裂化催化剂生产过程中分子筛粉碎技术的应用

在催化裂化催化剂生产过程中为了提高超稳分子筛的有效利用率,提升产品质量,使用了一系列超稳分子筛粉碎技术。对超稳分子筛聚集的原因及粉碎技术进行了对比分析,重点分析了介质超细研磨粉碎技术对催化剂质量指标的影响。造成超稳分子筛粒子聚集的主要原因是NaY分子筛合成过程中粒子间相互吸附,后续分子筛交换改性工序对分子筛粒度分布影响较小。介质超细研磨机和干磨粉碎技术对粉碎超稳分子筛效果明显,能够有效降低分子筛粒径,在催化裂化催化剂生产过程中介质超细研磨机的应用效果较好。经粉碎后的超稳分子筛能够明显降低催化裂化催化剂的磨损指数,提高微反活性。     

Fractal Extra-Framework Species in De-aluminated LaY Zeolites and Their Catalytic Activity

Lanthanum-containing Y (LaY) zeolites were prepared by ionic exchange from NaY parent zeolite. The LaY zeolites were de-aluminated by steaming. De-aluminated zeolites presented different Si/Al ratio. The physicochemical properties of these catalysts were characterized by X-ray diffraction, pyridine and xenon adsorption, infrared spectroscopy and ²⁹Si, ²⁷Al, ¹²⁹Xe, ¹³⁹La solid-state nuclear magnetic resonance spectroscopy. Furthermore, a fractal geometry approach was adopted to describe the evolution in the texture as a consequence of de-alumination. The catalytic properties of materials were evaluated in the n-hexane cracking reaction. The catalyst with the highest catalytic activity was the zeolite highest de-aluminated (Si/Al ratio of 3.7). Such performance was attributed on the one hand, to active extra-framework aluminum species hosted in the large cavities of zeolites and, on the other hand to redistribution of lanthanum species into the zeolite as a consequence of de-alumination.     

Predicting locations of non-framework species in zeolite materials

A new grid-based algorithm developed at Molecular Simulations, and molecular dynamics method have been applied to modeling the locations of non-framework species in zeolites. This new method locates the energy minima for various frameworks and populates these sites with the non-framework species. The cation locations were predicted in dehydrated zeolite adsorbents and catalysts, such as Na₈₈X, Ca₄₈X, mixed cation zeolite 3A (K₆₀Na₃₆A), and Cu-mordenite (Si/Al=5.0) using only well-known framework structure models. Furthermore, the locations of benzene molecules in a supercage of zeolite Ca₄₈X were correctly predicted via the application of the Monte Carlo docking and molecular dynamics methods.

These examples demonstrate that when the framework type is known, the new technique can provide a realistic initial structure input for the challenging task of solving crystal structures of zeolites containing non-framework species.     

Catalyst design and development for upgrading aromatic hydrocarbons

Background and strategy of catalyst development for upgrading aromatic hydrocarbons are intensively discussed. Originally prepared catalysts (hydrogenation and hydrocracking catalysts) were used for accelerated aging tests. Though each catalyst showed superior catalytic performance as compared to commercially available catalysts, a severe deactivation was observed on the hydrocracking (HC) catalysts. A new type of HC catalyst was designed and prepared, based on the understanding of catalyst deactivation. High silica NaY zeolites were synthesized using crown-ether. USY zeolites were then prepared by ion exchange, steaming and calcining. Surface properties and catalytic functions of well-crystallized USY zeolites were investigated to develop practical HC catalysts. The Ni–W catalyst prepared using the newly prepared USY zeolite showed a considerable improvement in the HC activity.     

Zeolite Y synthesized with FCC spent catalyst fines: particle size effect on catalytic reactions

In this study, Y zeolite with different particle sizes was synthesized with fines of Fluid Catalytic Cracking (FCC) spent catalyst. The effect of particle size on physicochemical properties of zeolite was systematically investigated. The results showed that zeolites synthesized via in situ crystallization technique exhibited large surface area, high relative crystallinity and high thermal stability. With a decrease of particle size of zeolite, both total acid density and B acid sites increased while acid L sites decreased. The cracking activity for heavy oil and coke resistance of ultra-fine zeolite catalysts were enhanced. Of note is that the desulfurization capability of superfine zeolite catalyst was found to be much higher than that of industrial catalyst.     

不同高岭土系黏土性质及在催化裂化催化剂中的应用

随着原料油重质化、劣质化程度逐渐增高,催化裂化催化剂基质不仅需要保证催化剂有良好的磨损性能和流化性能,还需要具有适当的孔和一定的酸性对原料油中的大分子进行预裂化。半合成催化裂化催化剂中的高岭土系黏土对催化剂性能有重要影响。高岭土可直接或经酸、碱改性作为催化剂基质,也可通过原位晶化技术合成分子筛或含有Y型分子筛的催化剂。累托石通过交联反应可以合成层柱分子筛用于催化裂化催化剂制备。埃洛石因其管状结构,作为基质时催化剂具有孔体积和比表面积大及活性高的特点。对催化裂化催化剂中高岭土系黏土结构、改性方法及在催化裂化催化剂中应用进行综述,并对今后高岭土在催化裂化催化剂中的研究方向进行展望。     

Degradation of CI Reactive Red 141 by heterogeneous Fenton‐like process over iron‐containing ZSM‐5 zeolites

The Fenton‐like oxidation of CI Reactive Red 141 was investigated over iron‐containing ZSM‐5 zeolites. Iron was loaded by ion exchange or through hydrothermal synthesis. The oxidation process was carried out in an aqueous solution using hydrogen peroxide as the oxidant. The catalyst prepared by ion exchange with a silicon/aluminium ratio of 42 zeolite showed the highest activity (97% decolorisation and 52% chemical oxygen demand reduction at an initial pH of 3.5) after an oxidation duration of 2 h. The chemical oxygen demand reduction increased with the increasing amount of iron loaded to the zeolite. The FeZSM‐5 catalyst, prepared by hydrothermal synthesis in the presence of oxalic acid, showed very good activity in terms of mineralisation (99% of chemical oxygen demand reduction). The iron leaching was noticeably low (below the European Union directives of 2 mg dm^?3) for the above‐mentioned catalysts.     

Hydrocracking of heavy oil using zeolites Y/Al-SBA-15 composites as catalyst supports

A series of Y/Al-SBA-15 composites were prepared by a two-step synthesis procedure in mild acidic medium. The materials were characterized by powder X-ray diffraction (XRD), N₂ sorption isotherms and TEM techniques. Catalytic cracking of cumene and 1,3,5-tri-isopropylbenzene was carried out as the probing reactions on these composites. The XRD results showed that these materials are composites of Al-SBA-15 and Y zeolite. N₂ sorption isotherms and TEM displayed that these composites were abundant in micropores and mesopores. At the same time, the mesopores may communicate with the␣micropores in some domains, which may result in the high catalytic activities of Y/Al-SBA-15 composites for the␣cracking of both small-molecule (cumene) and large-molecule (1,3,5-tri-isopropylbenzene) hydrocarbons. The existence of mesopores may also make the acid sites easily accessible for reactants. Catalysts of W–Ni supported on Y/Al-SBA-15 and modified Y zeolites with mesopores were prepared by impregnation method, and the hydrocracking of heavy oil was performed on these catalysts. The catalyst using zeolite Y/mesoporous Al-SBA-15 composites as support gave higher yield of diesel compared to the catalysts using modified zeolite Y as support. In addition, the higher aromatics potential of heavy naphtha and the significantly lower BMCI (U.S. Bureau of Correlation Index) of tail oil revealed Y/Al-SBA-15 composite catalyst possessed integrated performance in the hydrocracking of heavy oil. These results proved that the combination of Y zeolites and mesoporous Al-SBA-15 plays a great role in improving the performance of catalysts for hydrocracking heavy oils.     

Cracking of n-heptane over Brønsted acid sites and Lewis acid Ga sites in ZSM-5 zeolite

A series of gallium-containing ZSM-5 zeolites prepared by wet impregnation, ion-exchange and chemical vapor deposition (CVD) methods are compared in the cracking of n-heptane. Impregnation results in the dispersion of some of the gallium oxide clusters into the zeolite pore network as charge-compensating Ga species after calcination. Reduction of impregnated Ga/HZSM-5 catalysts leads to complete transformation of the oxidic Ga precursors to charge-compensating Ga⁺ and GaH²⁺ species. A small amount of divalent GaH²⁺ species can be stabilized; however, with increasing Ga/Al ratio monovalent cations dominate. While a model Ga/HZSM-5 catalyst prepared by CVD of Ga(CH₃)₃ containing mainly charge-compensating Ga cations displays high selectivity to dehydrogenated products (olefins, toluene and coke), catalysts with a lower Ga/Al ratio display improved activity with a product mixture resulting from contributions of Ga sites (dehydrogenation, aromatization, olefin cracking) and of Brønsted acid sites (protolytic cracking, olefin cracking). The synergy between Ga dehydrogenation sites and Brønsted acid sites is proposed to improve the dehydrogenation rate: the high acidity of the zeolitic proton facilitates hydrogen recombination and concomitant removal of product olefin from the Ga active sites. Ion-exchanged Ga/HZSM-5 catalyst which combines a difficult to reduce gallium oxide phase and high Brønsted acidity has the highest activity with relatively weak coke formation.     

酸性组分对LCO改质催化剂反应性能的影响

借助XRD,IR,NH3-TPD、N2 物理吸附等分析手段对4种改性Y沸石进行了表征.考察了不同酸性组分对LCO加氢改质催化剂反应性能的影响,结果表明分子筛硅铝比高,晶形完整,水热稳定性好以及较高的酸强度和较高的B酸浓度有利于催化剂维持较高的催化性能.最终确定了一种晶形完整、耐氮能力强及酸性高的改性Y分子筛为LCO改质催化剂的主要酸性组分.     

高分散纳米Y型分子筛负载Ni_2P催化剂的制备及其加氢脱硫性能

以无模板剂法合成的纳米Y型分子筛(35 nm左右)为载体,采用低温还原法制备了高分散Ni_2P/NY催化剂,同时制备了普通Y型分子筛担载的Ni_2P/Y催化剂作为对比。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线光电子能谱(XPS)等手段对载体和催化剂进行了表征,并在固定床反应器中考察了不同催化剂对4,6-二甲基二苯并噻吩(4,6-DMDBT)的加氢脱硫反应性能。结果表明,该催化剂的高活性来自纳米Y型分子筛上Ni_2P分散度的提高和高活性中心的暴露。在反应温度为340℃,反应压力为3.0 MPa的条件下,以Ni_2P/NY为催化剂,4,6-DMDBT的转化率达到了96.0%,高于CoMoS/Al_2O_3商业催化剂(77.2%)和Ni_2P/Y催化剂(67.0%)。     

改性Y分子筛加氢裂化催化剂耐氮性能的研究

采用水热处理法制备了两种改性Y型分子筛NTY和USY，并用含吡啶正庚烷和甲苯为模型化合物，对引入这两种分子筛制备的加氢裂化催化剂性能进行了考察，发现引入表面积大、二次孔多、结晶度高的NTY分子筛制备的加氢裂化催化剂，其耐氮性能明显优于USY分子筛制备的催化剂。     

ZSM-11分子筛的碱处理及其正十二烷催化裂解性能

研究了碱处理对ZSM-11分子筛的微观结构、酸性质和催化裂解性能的影响。采用不同浓度的氢氧化钠对ZSM-11分子筛进行碱处理,得到了级孔ZSM-11分子筛。用XRD,SEM,TEM, NH₃-TPD,N₂低温吸附-脱附等手段对碱处理后的分子筛进行了表征。以正十二烷为模型燃料,在550 ℃、4 MPa的条件下评价了分子筛的催化裂解性能。结果表明,碱处理导致HZSM-11分子筛晶粒内形成介孔、比表面积和酸量增加。碱处理的ZSM-11分子筛表现出较高的催化裂解活性。其中,用浓度为0.1 mol/L的氢氧化钠溶液处理的HZSM-11分子筛,催化活性最高。与未处理的HZSM-11分子筛相比,正十二烷的平均转化率提高了约58%。     

沸石孔结构对植物油催化裂化性能的影响

制备出硅铝比相近但介孔体积逐渐增加的超稳Y（USY）沸石，进而制备成微球状催化剂。本文在固定流化床装置上，考察了两种植物油的催化裂化性能。小桐子油的评价结果表明，催化剂中USY沸石的介孔体积越大，汽柴油收率越高；汽油族组成中烯烃收率越高，芳烃收率越低，汽油辛烷值和抗爆指数也越低；采用铵交换和水热改性制备介孔体积为0.142cm³/g的USY沸石催化剂的裂化产物中，汽柴油总收率为62.21%（质量分数），焦炭收率最低，汽油研究法辛烷值达到90.5；大豆油的催化裂化反应规律与小桐子油的一致，中等介孔催化剂裂化得到的汽油研究法辛烷值达到92.2。研究结果表明，采用催化裂化工艺，利用适当介孔的USY沸石催化剂，可以将植物油高效转化为车用轻质燃料，并且得到高辛烷值的汽油。     

多级孔分子筛在重油加氢裂化催化剂的应用进展

分子筛是加氢裂化催化剂关键组分,其性质影响着加氢裂化反应效率和产品分布。微孔分子筛的孔结构降低了大分子反应物的扩散效率和酸中心的可及性,不宜直接用作加氢裂化催化剂的载体。本文从分子筛的孔结构和酸中心可及性的角度出发,介绍了具有多级孔体系的分子筛和具有核壳结构分子筛的加氢裂化性能。与相应的参比剂比较,分子筛的多级孔结构能大幅提高反应物种的扩散效率和酸中心的可及性,呈现出更好的催化活性、稳定性以及目标产物选择性。此外,金属加氢活性中心与分子筛裂化活性中心的合理调配,也是多级孔分子筛在重油加氢裂化应用中面临的挑战。     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au catalysts is described and their activity is contrasted with silica- and alumina-supported Au catalysts. Two zeolites were investigated, ZSM-5 and zeolite Y. The effect of calcination of these catalysts is studied and it is found that for uncalcined catalysts high rates of hydrogen peroxide formation are observed, but these catalysts are unstable and lose Au during use. Consequently, reuse of these catalysts leads to lower rates of hydrogen peroxide formation. However, catalysts calcined at 400 °C are more stable and can be reused without loss of gold. The use of zeolites as a support for Au gives comparable rates of hydrogen peroxide formation to alumina-supported Au catalysts and higher rates when compared with silica-supported catalysts. prepared using a similar method. Zeolite Y-supported catalysts are more active than ZSM-5-supported catalysts for the stable calcined materials. It is considered that the overall activity of these supported catalysts may be related to the aluminium content as the activity increases with increasing aluminium content.