Sheng-Li Chen

Mild cracking solvent deasphalting : a new method for upgrading petroleum residue

Abstract A new process—mild cracking solvent deasphalting (MCSD)—is described for upgrading heavy oil. Continuous bench experiments were carried out on Shengli and Gudao vacuum residues. The effects of cracking temperature and time on the yield, Conradson carbon residue, nickel content of deasphalted oil and properties of raffinate asphalt were examined. The deasphalted oil (DAO) obtained by MCSD was superior in yield and quality to that from solvent deasphalting alone. At the same yield of DAO, the softening point of the raffinate asphalt was lower and the penetration and the ductility were greater than those for the solvent deasphalting process.

Synthesis and Catalytic Hydroisomerization Performance of SAPO-11 Molecular Sieve with Small Crystals

Abstract On the basis of the conventional hydrothermal method, the small crystal SAPO-11 molecular sieves with sub-micron size were synthesized by controlling the aging conditions of the synthesis gel and without using other organic additives except for the template. The particles of the samples synthesized by this method possessed much smaller crystal dimension and were more uniform in size than conventionally synthesized samples. The crystal morphology of the SAPO-11 samples synthesized by the improved hydrothermal method exhibited in cube shape with particle size in the range of 400–500 nm, whereas for the SAPO-11 synthesized by the conventional method, pseudo-spherical aggregates ranging from 7 to 10 μm were obtained. The sample synthesized by the improved method had larger BET surface area and larger external surface area than that of the samples prepared by the conventional hydrothermal method. The results of n -hexadecane hydroisomerization showed that the Pt/SAPO-11 catalysts synthesized by the improved method exhibited both higher catalytic activity and higher hydroisomerization selectivity than the catalysts synthesized by the conventional hydrothermal method.

Influence of template content on selective synthesis of SAPO-18, SAPO-18/34 intergrowth and SAPO-34 molecular sieves used for methanol-to-olefins process

SAPO-18, SAPO-18/34 intergrowth and SAPO-34 molecular sieves have been selective synthesized using different amount of template (tetraethyl ammonium hydroxide, TEAOH). The samples were characterized by XRD, XRF, TG-DSC, 13C (29Si) CP/MAS NMR and NH3-TPD. The synthesized products switched from SAPO-5/18, to SAPO-18, SAPO-18/34, and finally to SAPO-34 with the increasing of TEAOH amount. The TEAOH in SAPO-18 cages mainly acted the role of space filling. While in SAPO-34, the TEAOH was mainly used to compensate the negative charge of the framework. SAPO-34 possessed much more Si(4Al) structure compared to SAPO-18 and SAPO-18/34. For methanol to olefins reaction, SAPO-18 yielded the highest propene and C4 than that over SAPO-18/34 and SAPO-34, SAPO-34 had the highest ethene yield among the three catalysts. The working lifetimes of SAPO-18/34 and SAPO-34 were significantly longer than that of SAPO-18.

Metathesis of 1-butene and 2-butene to propene over Re2O7 supported on macro-mesoporous γ-alumina prepared via a dual template method

Abstract Macro-mesoporous γ-alumina support (MMA) was prepared by a sol-gel route in aqueous medium using pseudo-boehmite as aluminum source and polystyrene microspheres and Pluronic P123 as hard and soft dual templates, respectively. MMA had a BET specific surface area of about 259 m2·g−1, total pore volume of about 1.61 cm3·g−1, macropore diameter of about 102 nm, and mesopore diameter of about 14 nm. Re2O7/MMA and conventional Re2O7/Al2O3 were prepared by a incipient-wetness impregnation method, and their catalytic performances in the metathesis of 1-butene and 2-butene were tested in a fixed-bed tubular reactor. The result showed that Re2O7/MMA possessed higher activity and far longer working life-span than conventional Re2O7/Al2O3.

Preparation of Macroporous Al2O3 by Template Method

Abstract Macroporous Al 2 O 3 was prepared through mixing Al 2 O 3 sol with polystyrene (PS) particles as templates, drying the suspension, and finally calcining it to remove the templates. The measurement obtained from the scanning electron microscope (SEM) showed that the formed macroporous materials had a vesicle-like structure and most of the voids left by the templates were isolated from each other. The Zeta-potential value indicated that the PS particles carried negative charges, whereas the alumina particles carried positive charges. During the preparation of macroporous Al 2 O 3 , the Al 2 O 3 colloidal particles were adsorbed onto the surface of the PS particles, and the PS with the shell of Al 2 O 3 particles played the role of templates, resulting in the formation of vesicle-like structures. To avoid the formation of vesicle-like structure material, the PS was switched from a negative charge to a positive charge through surface modification with PD (poly(diallyl-dimethyl ammonium chloride)) so that the PS particles carried the same kind of charges as the Al 2 O 3 colloidal particles. The SEM images showed that the macroporous material of Al 2 O 3 , prepared using the modified PS spheres as templates, was free from the vesicle-like structure and voids left by the templates were connected through some windows.

Preparation of mesoporous alumina with large pore size and their supported rhenium oxide catalysts in metathesis of 1-butene and 2-butene to propene

Abstract Mesoporous γ-aluminas with large pore size (up to 19 nm, denoted as MA19) are prepared from dispersed pseudo-boehmite using pluronic P123 as template. It is found that these mesoporous alumina supported rhenium oxide catalysts were more active and have far longer working life-span in gas-phase metathesis of 1-butene and 2-butene to propene than rhenium oxide on conventional alumina with small pore size (5 nm). At 60°C and atmospheric pressure with WHSV= 1 h −1 , the similar stable conversions of butene (ca. 55%) for all the 13 wt% Re 2 O 7 /alumina catalysts were obtained near the chemical equilibrium, and the stable working life-spans of Re 2 O 7 /MA19 were far longer than that of Re 2 O 7 /Al 2 O 3 , being about 70 h and 20 h, respectively.

Synthesis of ZSM-5 and its application in butylene catalytic cracking

Abstract The template-free ZSM-5 was prepared by hydrothermal synthesis and then modified by tetramethoxysilane (TMOS). The structure, morphology, and acidity of all samples were studied by various techniques, such as XRD, SEM, 29 Si MAS NMR, 27 Al MAS NMR, NH 3 -TPD, BET and UV-vis DRS. Comparing with the zeolites synthesized by traditional method, the template-free ZSM-5 exhibited the analogical acidity, morphology and structure, but obvious difference in acid distribution. Due to the absence of the structure directing agent, the template-free ZSM-5 possessed more acid sites situated at pore channels of catalyst and less acid sites stayed at the intersection of straight and sinusoidal channels. Consequently, the shape selectivity enhanced significantly. After TMOS modification, the non-shape acid sites located at the external surface were covered by a single SiO 2 layer. The template-free ZSM-5 achieved the highest total yield of ethylene and propylene, longest working life-span and lowest level of coke deposition among the studied catalysts, ascribing to the suppression of the side reactions.

Influence of catalyst support structure on ethene/decene metathesis and coke formation over WO3/SiO2 catalyst

Abstract8wt%WO3/SiO2 metathesis (disproportionation) catalysts with different pore structures were prepared by the incipient-wetness-impregnation method. The as-synthesized catalysts were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS) and scanning transmission electron microscopy-high-angle annular dark field (STEM HAADF). The results of STEM HAADF showed that WO3 species were not uniformly distributed on the SiO2 support. The experimental results of 8wt%WO3/SiO2 performance in ethene/decene metathesis revealed that the catalytic effect of 8wt%WO3/SiO2 catalyst and coke formation over it were closely related to the support pore structure: The 8wt%WO3/SiO2 catalyst with a more complicated pore structure showed better catalytic performance but the coke deposition rate was also faster.

Preparation and evaluation of a well-ordered mesoporous nickel-molybdenum/silica opal hydrodesulfurization model catalyst

A silica-supported hydrodesulfurization (HDS) model catalyst with well-ordered pore structure was prepared by depositing Ni and Mo on the surface of silica opal. Using the voids of ordered packing of monodisperse silica microspheres, the pores of the model catalyst are wholly open-through and uniformly distributed. The ordered pore structure and regular smooth surface of the model catalyst make the surface states of metal oxides readily observable. As a result, the metal oxides were well dispersed on the silica, and the model catalyst exhibited a high activity in HDS of dibenzothiophene.

Synthesis of mesoporous MCM-48 molecular sieves of high quality in a fluorine-containing system

Abstract Mesoporous MCM-48 molecular sieves were synthesized in a fluorine-containing system using tetraethylorthosilicate (TEOS) as silica source and cetyltrimethylammonium bromide (CTAB) as template. To investigate the influence of various factors for synthesis on the structure and properties of the MCM-48 molecular sieves obtained, they were characterized by X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscopy (TEM). The results showed that under the optimal conditions, i.e. a CTAB/Si ratio of 0.65 and crystallization at 393 K for 24 h, the as-synthesized MCM-48 exhibits high crystallinity with a specific surface area of 1305 m2/g and an average pore size of 2.416 nm.