Effect of zeolite, kaolin and alumina during cracking of heavy petroleum residue evaluated by thermogravimetry

This work evaluates the effect of the FCC catalyst components—Y zeolite, kaolin and alumina—on the formation of coke during the cracking of heavy residue (HR) of petroleum. The Y zeolite, kaolin and alumina were mixed with a HR at a ratio of approximately 1:4. The effect was studied using dynamic thermogravimetry at a heating rate of 50 K min⁻¹, with N₂ (between 35 and 700 °C) and air (in the 700–1,000 °C temperature range). The HR analyzed in these conditions formed 8.1% of coke. All the mixtures presented larger coke formation than that observed in pure HR. The Y zeolite presented fourfold larger coke formation, while kaolin and alumina showed twofold higher formation than pure HR. The major focus of this study was to verify the sensitivity of the TG technique in providing information about coke formation in the fluid catalytic process of refineries.     

Catalytic Performances of Binder-free ZSM-5 Catalysts for Dehydration of Crude Methanol to Dimethyl Ether

A series of binder‐free ZSM‐5 catalysts and a binder‐containing catalyst were prepared and characterized with X‐ray diffraction (XRD), X‐ray fluorescence (XRF), ²⁷Al magic‐angle spinning (MAS) nuclear magnetic resonance (NMR), N₂ sorption and ammonia temperature‐programmed deposition (TPD) methods. The catalytic activity and selectivity in the dehydration of crude methanol to dimethyl ether (DME) were evaluated in a fixed‐bed reactor for the catalysts. The outstanding structural characters such as high zeolite contents, sufficiently open channels and richness in mesopores have been proved on these binder‐free catalysts. The influence of the solid‐acidity, which is closely related to the framework silica alumina ratio (SAR) of the catalysts, on the catalytic properties has been discussed. A binder‐free catalyst with a better potential in application has been selected for its high activity and selectivity, long life‐time and non‐sensitivity to water contents in the feed. The reason for its excellent performance of the catalyst was discussed.     

Effects of binder, coking and regeneration on acid properties of H-mordenite during TDP reaction

The effects of binder, coking and regeneration on the acid properties of H-mordenite zeolite during toluene disproportionation reaction (TDP) have been investigated by solid-state ³¹P-MAS-NMR of various adsorbed phosphorous probe molecules in conjunction with elemental analysis by ICP-MS technique. A series of fresh, spent and regenerated mordenite-based commercial catalysts were examined and the results were also compared with binder-free H-mordenite zeolite and unformulated γ-alumina binder. It is found that parent H-mordenite zeolite possessed only Brønsted acidity, which is responsible for the observed catalytic activity. In contrast, the γ-Al₂O₃ binder exhibited only Lewis acidity and plays a minor role during the catalytic reaction. While the amount of strong Brønsted acid sites decreased rapidly during initial coking, it reached a plateau at a total coke content of ca. 7 wt%, corresponding to ca. 80% decrease in total acidity. That the catalyst remained active even under deep coke deposition (>7 wt%) condition indicated catalytic activity may be invoked by subsequent coking taking place on the external surface rather than intracrystalline channels of the zeolite catalyst. Furthermore, upon catalyst regeneration treatment, ca. 75% of the total acidity could be effectively recovered.     

Lithium-ion conduction in elastomeric binder in Li-ion batteries

This paper describes two kinds of elastomeric binders which are styrene–butadiene (ST–BD) copolymer and 2-ethylhexyl acrylate–acrylonitrile (2EHA–AN) copolymer for electrode materials of rechargeable Li-ion batteries. These elastomeric binders were swollen by electrolyte solution (EC/DEC=1/2, 1 M LiPF₆), and 2EHA–AN copolymer retained larger amount of electrolyte solution than ST–BD copolymer. The Li-ionic conduction behavior was investigated for both copolymer films swollen by electrolyte solution. The Li-ion conductivity of ST–BD copolymer was 9.45 × 10⁻⁸ S·cm⁻¹ and that of 2EHA–AN copolymer was 1.25 × 10⁻⁵ S·cm⁻¹ at room temperature, and the corresponding amounts of activation energy were 0.31 and 0.26 eV, respectively. Because the observed activation energy in elastomeric binder was different from that in the bulk of electrolyte solution (0.09 eV), Li-ion conduction of the bulk of elastomeric binder swollen by electrolyte was affected by the polymer structure of binders. Electrochemical performance of cathode material, LiCoO₂, was investigated with three kinds of binders: ST–BD copolymer, 2EHA–AN copolymer, and poly(vinylidene fluoride). The initial charge–discharge capacity of the LiCoO₂ electrode with 2EHA–AN copolymer showed highest capacity, suggesting that Li⁺-ion conduction inside of the elastomeric binder contributes to the enhancement of charging and discharging capacity. This result indicates that elastomeric binder with sufficient Li-ionic conductivity can be an attractive candidate for improving cathode of lithium-ion battery.     

Structures of active sites for alkane transformations over the Pt/HZSM-5 and Pt/NaZSM-5 catalysts

The structure and reactivity of Pt₆ particles in the sodium and hydrogen forms of the ZSM-5 zeolite were investigated by the DFT method. Upon adsorption on the sodium form, the interaction energy is 15 kcal mol⁻¹ and a negative charge appears on the metal cluster. In channels of the hydrogen form, the adsorption energy of the metal particle increases to 45 kcal mol⁻¹ and the oxidized states of platinum are formed. The formation of an active site in the H-form of the zeolite involves the interaction of the platinum particle with the acid site resulting in the suppression of the acidity of the support. An alternative mechanism of alkane transformations avoiding acid site participation was proposed. A possibility to envisage the direction of the transformation of alkanes adsorbed on the metal particles was shown. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1139–1144, June, 2008.     

载体H+含量对CuY甲醇氧化羰基化反应性能影响

通过过量浸渍Cu(NO_3)_2溶液于Y分子筛载体上,制备出Cu负载量为6.4%的CuY催化剂,考察了甲醇氧化羰基化反应的催化性能,并采用X射线衍射(XRD)、H2程序升温还原(H2-TPR)、透射电子显微镜(TEM)和NH3程序升温脱附(NH3-TPD)等手段对催化剂表面微观结构进行了表征。研究表明,随Y分子筛载体H+含量的增加,可使更多Cu物种落位于分子筛微孔笼结构中,且高度分散,而笼内未交换的Na+能进一步促进铜物种更多落位于载体超笼结构中,形成更多甲醇氧化羰基化反应的Cu+活性中心。同时随铜物种引入,催化剂中产生了明显的中强酸,酸量随落位于载体笼结构中的Cu物种的增加而增加,催化剂总酸量随之增加,导致甲醇氧化羰基化产物分布发生改变,碳酸二甲酯(DMC)选择性明显降低。对比等体积浸渍法制备的92.3%的高DMC选择性CuY催化剂,以不含H+的NaY分子筛为载体,过量浸渍法制备的CuY催化剂酸量少、Cu物种活性中心多,在保持82.4%的高DMC选择性时,其DMC的时空收率(STY)也高达109.1mg·g~(-1)·h-1。     

Ceramic honeycombs coated with zeolite Co-ZSM-5 for Nox abatement

A deNO_x catalyst was prepared by wash-coating a cobalt ion exchanged ZSM-5 zeolite together with an alumina binder on a cordierite honeycomb structure. A few types of the Co-ZSM-5 based catalysts were tested for NO_x reduction with C₂H₄ under oxidizing conditions in the temperature range between 250–600°C. Preliminary tests of the catalytic activity of the systems showed NO_x reduction up to 95% at temperatures between 400–550°C using a mixture of a synthetic gas and air as reactant.     

Catalytic properties of Pt/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts in the aqueous-phase reforming of ethylene glycol: Effect of the alumina support

The influence of the alumina support on the catalytic activity of Pt/Al₂O₃ catalysts in aqueous phase reforming of ethylene glycol to hydrogen was studied. The catalysts were prepared by impregnation of γ-, δ-, and α-alumina with H₂PtCl₆. The highest rate of hydrogen production (452 μmol min⁻¹ g⁻¹) obtained with the Pt/α-Al₂O₃ catalyst can be related to the highest extent of dispersion of Pt on α-Al₂O₃. XPS, TEM-EDX and TPR-H₂ measurements showed the absence of chloride-containing surface complexes in the Pt/α-Al₂O₃ catalyst. However, chloride-containing entities were found on the surface of Pt/γ-Al₂O₃ and Pr/δ-Al₂O₃ catalysts. When chloride ions are removed chlorinated Pt species facilitate the sintering of Pt crystallites and in this way affect the extent of Pt dispersion. Moreover, depending upon the particular crystalline form, alumina atoms have different coordination and alumina surfaces contain varying amounts of OH groups of different nature which affect the interaction between Pt and the support.     

Treatment of acidic palm oil for fatty acid methyl esters production

Acidic crude palm oil (ACPO) produced from palm oil mills with an acid value of 18 mg g⁻¹ was considered to be a possible feedstock for biodiesel production. Due to its high acidity, conventional transesterification cannot be applied directly for biodiesel production. Methane sulphonic acid (MSA, CH₃SO₃H) is used to reduce the acidity prior to the alkaline transesterification reaction. The laboratory-scale experiments involved an MSA to ACPO dosage of 0.25–3.5 %, a molar ratio (methanol to ACPO) from 4: 1 to 20: 1, reaction temperature of 40–80°C, reaction time of 3–150 min, and stirrer speed of 100–500 min⁻¹. The optimum esterification reaction conditions were 1 % of catalyst to ACPO, with a molar ratio of methanol to ACPO of 8: 1, a stirring speed of 300 min⁻¹, for 30 min and at 60°C. Under these conditions, the FFA content was reduced from 18 mg g⁻¹ to less than 1 mg g⁻¹ and with a yield of 96 %. The biodiesel produced met the EN14214 standard specifications. MSA was recycled for three times without losing its activity. The biodiesel produced in a two-stage process has a low acid value (0.14 mg g⁻¹).     

介孔调变对CuY催化剂甲醇氧化羰基化反应活性的影响

碱溶液处理NaY分子筛形成的介孔有利于反应物及产物分子的扩散,调节碱溶液浓度可控制Y分子筛中的介孔结构,通过溶液离子交换法制备CuY催化剂,研究了NaY分子筛介孔结构调变对CuY催化剂催化甲醇氧化羰基化反应活性的影响。通过BET、~(29)Si-NMR、XRD、NH_3/CO-TPD、H_2-TPR和TEM等表征及催化活性分析表明,在碱溶液处理过程中,NaY分子筛骨架中的Si(0Al)和Si(1Al)原子被优先脱除,且笼结构坍塌使得临近超笼连接,逐步形成直径为3.47~3.66 nm,孔容介于0.142~0.226cm~3·g~(-1)的介孔,在提高反应物分子和产物分子扩散性能的同时,提高了活性物种的可接近性。随着碱液浓度的增加,CuY催化剂的催化活性先升高后降低。当碱液浓度为0.2 mol·L~(-1)时,NaY分子筛介孔直径为3.47 nm,孔容达到最大(0.226 cm~3·g~(-1)),相应CuY催化剂DMC的时空收率、选择性和甲醇转化率分别达到204.0 mg·g~(-1)·h~(-1)、67.8%和14.0%,活性最佳。     

Ship-in-a-bottle formation of Ru3(CO)12 in zeolite NaY

A NaY zeolite entrapped Ru₃(CO)₁₂ cluster has been synthesized from RuCl₃ ionexchanged NaY, which are well characterized by IR and Raman spectroscopy and CO chemisorption. When the Ru³⁺/NaY sample is heated from 298 to 393 K for 25 h and kept for 10–20 h at 393 K, the sample color changes from dark to brown-yellow. Thein situ infrared spectrum exhibits bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm⁻¹. The bands at 2064, 2040, 2017 and 1990 cm⁻¹ are assigned to Ru₃(CO)₁₂/NaY, which are close to crystalline Ru₃(CO)₁₂. Furthermore, Raman results provide the bands at 150 and 185 cm⁻¹, which are attributed to Ru-Ru bonds of crystalline Ru₃(CO)₁₂). CO chemisorption on [Ru₃]/NaY gives a CO/Ru ratio of 3.85, which is similar to the stoichiometry of Ru₃(CO)₁₂ (CO/Ru=4.0).     

MOR/SBA-15复合分子筛的合成、表征及其催化性能评价

采用MOR纳米晶和正硅酸四乙酯为硅源,P123三嵌段共聚物为模板剂水热合成MOR/SBA-15复合分子筛催化剂。采用XRD、SEM、TEM和EDX等手段对催化剂进行了表征,在固定床反应器中评价二甲醚制乙醇催化性能。结果表明,通过控制合适的MOR纳米晶种及MOR纳米晶种在SBA-15水热合成体系中的添加量,可以成功地将MOR纳米晶作为SBA-15的结构单元嫁接到SBA-15的介孔骨架中,水热合成的MOR/SBA-15复合分子筛催化剂同时具有MOR和SBA-15的XRD特征衍射峰,相比于SBA-15,其比表面积和总孔体积由756 m2·g~(-1),1.07 cm3·g~(-1)降低至628 m2·g~(-1),0.85 cm3·g~(-1),平均孔径由8.1 nm提高到9.3nm,Cu修饰的MOR/SBA-15复合分子筛催化剂同时具有Cu MOR羰基化和Cu SBA-15加氢的双功能催化性能,其催化剂评价结果显示二甲醚转化率为43.6%左右,乙醇选择性为95.3%,Cu MOR/SBA-15复合分子筛催化剂实现了二甲醚到乙醇的一步转化。     

Adsorption properties of BEA zeolites and their aluminum phosphate extrudates for purification of isomaltose

The disaccharide isomaltose is produced via an enzymatic reaction and is adsorbed to BEA zeolite. This reaction integrated adsorption can be achieved as fluidized bed as well as fixed bed. We investigated isotherms, adsorption enthalpies and sorption kinetics of BEA zeolite and extrudates with a novel aluminum phosphate sintermatrix. These extrudates contain 50% (w/w) of BEA 150 zeolites (Si/Al = 75) as primary crystals. BET-surface for extrudates is 245 m²⋅g⁻¹ and 487 m²⋅g⁻¹ for zeolite. Extrudates show a monomodal macropore structure with a maximum at 90 nm. All isotherms show a type I shape. For lower equilibrium concentrations, which occur during the enzymatic reaction, Henry’s law is applied and compared to a Langmuir model. Adsorption equilibrium constant K _i,L calculated from Langmuir for extrudates at 4 °C is 64.7 mL⋅g⁻¹ and more than twice as high as obtained from Henry’s law with K _i is 26.8 mL⋅g⁻¹. Adsorption on extrudates at 4 °C is much stronger than on zeolite crystals where the Henry coefficient K _i is 17.1 mL⋅g⁻¹. Adsorption enthalpy Δh _Ad calculated from van’t Hoff plot with the Henry equation is −44.3 kJ⋅mol⁻¹ for extrudates and −29.6 kJ⋅mol⁻¹ for zeolite crystals. Finally, the kinetics for ad- and desorption were calculated from the initial slope. The diffusion rate for ad- and desorption on extrudates were in the same range while adsorption on zeolites is three orders of magnitudes faster than desorption.     

Adsorption and catalytic conversion of hydrocarbons on nanosized gold particles immobilized on alumina

Gold and nickel particles immobilized on alumina were prepared by the metal vapor synthesis and anionic adsorption methods. The dispersion of metals was determined by X-ray diffraction and transmission electron microscopy. The activity of nanoparticles, tested in model catalytic reactions of CCl₄ addition to multiple bonds and allyl isomerization of allylbenzene, changes in a wide range (from 1 to 3000 (mole of product) (mole of Au)⁻¹ h⁻¹) and is parallel to the chromatographically measured heats of adsorption of the corresponding unsaturated substrates. The heat of adsorption of unsaturated hydrocarbons can serve as a criterion for the efficiency of the gold-containing catalyst in olefin conversion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2215–2218, October, 2005.     

Isomerization of n-Hexane Over Platinum Ion-Exchanged Zeolite Beta

Zeolite Beta was synthesized from appropriate gels and crystallized under the controlled temperature and pressurized conditions. For isomerization of n-hexane, platinum ion-exchanged zeolite Beta exhibited high activity and selectivity for 2,2-dimethylbutane (2,2-DMB), 2,3-dimethylbutane (2,3-DMB), 2-methylpentane (2-MP) and 3-methylpentane (3-MP). As high as 72% of n-hexane conversion and 98% of product selectivity were obtained at 250°C, 1600 h^–1 for 20 min on stream. The influences of reaction temperature and space velocity were also studied. Pt/H-Beta zeolite was recommended as one of the promising catalyst for n-hexane isomerization due to its high activity and stability. The combined effect of the stronger acidity possessed by H-Beta and the dehydrogenation role played by Pt was believed to be responsible for the good catalytic performance of Pt/H-Beta.     

Effect of Ba2+ ion exchange in the Pt/BaKL reforming catalyst

Calcination of BaKL zeolite causes Ba²⁺ ions to migrate to the locked exchange sites. Meanwhile, Pt²⁺ ions in Pt/BaKL zeolite are also located in these sites because of Ba−O−Pt interaction. Therefore, the reduced Pt/BaKL exhibits better dispersion of Pt particles and improved reactivity inn-hexane aromatization than Pt/KL zeolite.     

Catalytic pyrolysis of low density polyethylene over H-β, H-Y,H-Mordenite,and H-Ferrierite zeolite catalysts: Influence of acidity and structures

Low-density polyethylene (LDPE) catalytic pyrolysis was investigated over H-β-25, H-β-150, H-β-300, H-Y-12, H-Mordenite-20, and H-Ferrierite-20 zeolite catalysts. The numbers denote the SiO₂/Al₂O₃ molar ratios. The influence of the zeolite’s acidity on the transformation of LDPE was studied by varying the SiO₂/Al₂O₃ molar ratios of the β zeolite. The influence of the zeolite structure was investigated by using the proton forms of Y, β, Mordenite, and Ferrierite zeolites. The catalysts were characterized using X-ray powder diffraction patterns, nitrogen adsorption, and FTIR spectroscopy with pyridine as the probe molecule. The large pore and least acidic H-β-300 catalyst showed the lowest activity in the catalytic pyrolysis of LDPE. The H-β-25 catalyst, with higher acidity than H-β-300, showed higher activity for LDPE pyrolysis than H-β-300, indicating the importance of strong acid sites for this reaction. The H-Ferrierite and H-Mordenite catalysts, with small pores, showed the lowest effect on LDPE pyrolysis, although the catalysts were more acidic than H-β-25 and H-β-150, indicating that not only acidity but also the structure and pore size of zeolites are important for pyrolysis of LDPE. However, the H-Y zeolite catalyst with large pores and cavities is not suitable for this reaction because of rapid deactivation due to coke formation. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 4, pp. 570–575. This article was submitted by the authors in English.     

薄片状MFI晶体无凝胶蒸汽辅助晶化制备b轴取向沸石膜

采用新型薄片状MFI沸石晶体作为晶种,通过无凝胶蒸汽辅助晶化法(gel-less steam-assisted crystallization,GLSAC)在烧结氧化硅多孔载体上制备了致密平整、b轴取向的MFI沸石膜。考察了GLSAC中模板剂浓度、釜底水量、生长温度及时间对MFI沸石膜的影响。扫描电子显微镜和X射线衍射结果显示,适量的模板剂和釡底水量能抑制晶种的面外生长。成功制备了厚度750 nm、致密平整的MFI沸石膜。制备的对丁烷异构体气体分离测试表明,25℃时,等物质的量的丁烷异构体的分离因子(SF_A/B)可达36,对正丁烷的渗透速率为1.5×10^-7mol·m^-2·s^-1·Pa^-1。     

High resolution adsorption isotherms of N2 and Ar for nonporous silicas and MFI zeolites

The high resolution adsorption isotherms of N₂ (77.4 K) and Ar (87.3 K) have been measured for two nonporous silicas with different silanol contents (3.3 and 0.35 OH/nm²) and for two MFI zeolite with different Al contents (Si/Al=12.5 and 500). Silanol groups and Al sites (acid sites) gives the significant effect on the N₂ isotherms at submonolayer, but the Ar isotherms are independent of silanols and Al sites. The Ar isotherms, therefore, are preferable in calculation of microporosity of zeolites. The N₂ and Ar isotherms for MFI zeolite (Si/Al=500) have been measured at temperatures of 77–94 K, from which the differential adsorption energies of N₂ and Ar are calculated. The interaction of N₂ with channel surface of MFI zeolite is greater than that of Ar in the range of α _s =0.1–0.7. The hystereses are detected for the N₂ isotherm in p/p ^o=0.1–0.3 at 77.4 K and for the Ar isotherm in p/p ^o=3×10⁻⁴–2×10⁻³ at 87.3 K. However, it is difficult to explain the hysteresis phenomenon using differential adsorption energy.     

晶种导向干凝胶法制备成型ZSM-5分子筛

在干凝胶法制备ZSM-5 分子筛的体系中添加晶种导向剂, 控制分子筛的生长, 制备了纳米沸石组装的无粘结剂成型多级孔ZSM-5 分子筛, 一步完成纳米分子筛的制备及组装成型, 即克服了传统纳米粒子难以过滤分离的问题, 同时组装所形成的多级孔有助于改善分子在催化剂内的扩散, 从而提高催化反应效率. 以硅胶、薄水铝石为原料, 四丙基氢氧化铵(TPAOH)和ZSM-5 晶种导向胶作为粘结剂, 通过混捏、挤条得到直径2 mm的条状前驱物, 随后通过干凝胶转换法制备成型分子筛. 所用晶种导向剂组成为0.35TPAOH:1SiO₂:20H₂O:4C₂H₅OH. 通过X射线衍射(XRD), 热重(TG)分析和傅里叶变换红外(FTIR)光谱等方法对分子筛晶化过程进行了表征, 结果表明晶种导向剂加入量对分子筛生长速度及多级孔结构均有影响. 当所加晶种导向剂中TPAOH与SiO₂的摩尔比为0.025时, 经过3 h晶化, 分子筛相对结晶度达到100%. 扫描电镜(SEM)结果表明, 合成的分子筛尺寸约为200 nm, 组装形成的多级孔分子筛的介孔体积为0.28 cm³·g^-1. 通过NH₃ 程序升温脱附(NH₃-TPD)考察了所得成型分子筛的酸性, 发现该分子筛酸性与市售的粉末H-ZSM-5分子筛类似.