Series Of ZSM-5 Research Articles

Preparation and high CO2/CH4 selectivity of ZSM-5/Ethyl cellulose mixed matrix membranes

It is known that natural gas is extracted with a large amount of CO2, which reduces the amount of heat generated during the combustion of natural gas. How to remove some of the CO2 from the natural gas is a problem that needs to be solved. The significant breakthroughs of the membrane technology, specifically the mixed matrix membrane (MMM) has revealed a promising CO2/CH4 separation performance. In this study, a series of ZSM-5/EC mixed matrix membranes with ethyl cellulose (EC) as matrix and ZSM-5 as inorganic dispersant in tetrahydrofuran were prepared under high speed and ultrasonic vibration-assisted, the ZSM-5/EC membranes were fabricated by using the casting solution. The successful ZSM-5/EC mixed matrix membranes were confirmed by Fourier transfer infrared (FTIR) and Scanning electron microscopy (SEM). The ZSM-5/EC membranes exhibited good membrane forming ability, heat resistance and mechanical properties; The CO2/CH4 selectivity of the ZSM-5/EC membranes were 10.7, 15.4, 19.7, 25.5 and 11.7, respectively, increased up to 1.3, 1.9, 2.4, 3.1 and 1.4 times as compared to pure EC (8.20) with a feed composition of 50:50 for CO2/CH4.

Tuning physicochemical properties of hierarchically ZSM-5/FDU-12 composite material and its catalytic hydrodesulfurization performance for diesel

A series of ZSM-5/FDU-12 (ZF-x) composite material with MFI microporous structure and face-centered cubic structure were successfully synthesized using the nano-assembly method under different water bath temperatures. The bath temperature had an apparent influence on the material’s physical texture property. The catalytic hydrotreating performance were evaluated inside fix-bed unit, under the reaction conditions of 5 MPa and 350 °C. The sulfur and nitrogen contents of the products obtained from NiMo/ZFA-30 catalyst were reached 11.5 ppm and 4.8 ppm, respectively. The moderate acidity and the highest sulfidation ratio of active phases were responsible for the highest hydrodesulfurization (98.9 %) and hydrodenitrogenation (99.3 %) efficiency over the NiMo/ZFA-30 catalyst.

Effects of acid pretreatment on Fe-ZSM-5 and Fe-beta catalysts for N2O decomposition

Two series of ZSM-5 and beta zeolites were pretreated in 1.0 mol/L HNO3 solution at room temperature for various time periods. The catalytic performances of their Fe-exchanged products in N2O decomposition were evaluated. The Fe-zeolite catalysts were characterized using N2 adsorption-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, ultraviolet-visible spectroscopy, temperature-programmed desorption of NH3, and scanning and transmission electron microscopies. For the ZSM-5 zeolite, acid leaching primarily takes place on the crystal surface and the particle size is reduced, therefore the pore channels are shortened. However, because of the good stability of MFI zeolites, the acid does not greatly penetrate the pore channels and new mesopores are not created. For the beta zeolite, because the amorphous material is inclined to dissolve (deagglomerate), some of the micropores are slightly dilated. The improved catalytic activities can be explained by the increased active Fe loading as a result of structural changes.

The Effect of Pretreatment Method on the Preparation of Micro-mesoporous ZSM-5/Y-Al2O3Composite Materials

A series of ZSM-5/γ-Al 2 O 3 composite materials were prepared under various pretreatment method; The physicochemical properties of composite materials were investigated by XRD, SEM, FTIR to find out optimal pretreatment method. The results showed that the composite materials performance better structure property when γ- Al 2 O 3 was firstly immersed in TPAOH solution under reflux condensation for a period of time and then immersed into anhydrous alcohol before mixed with ZSM-5 precursor solution. The result of infrared spectrum indicated that the formation of Al-OH bond played a key role in the synthesis of micro-mesoporous ZSM-5/γ-Al 2 O 3 composite materials.

A preliminary evaluation of ZSM-5/SBA-15 composite supported Co catalysts for Fischer–Tropsch synthesis

A series of ZSM-5/SBA-15 composite supported Co catalysts were prepared and evaluated for the Fischer–Tropsch synthesis (FTS) aimed to maximise the selectivity of C5–C22 hydrocarbons in the product. The composite support was prepared by physically mixing ZSM-5 and SBA-15 of varying proportions and the finished catalysts had a constant Co loading of 15wt.%. The catalysts were tested for their performance in a high pressure fixed-bed reactor operating at T=240°C, P=2.0MPa, H2/CO=2 and GHSV=1000h−1. The composite supported catalysts were shown to have much improved catalytic performance over the respective single material supported catalysts. The catalyst with 20wt.% ZSM-5 in the composite support gave the maximum CO conversion (90.6%), maximum selectivity of C5–C22 hydrocarbons (70.0%) and minimum selectivity of light hydrocarbons (13.3% for CH4 and 7.0% for C2–C4 alkanes). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy with an energy dispersive X-ray spectrometer, temperature programmed desorption and temperature programmed reduction. It was revealed that the superior catalytic performance can be attributed to the large pore size and high dispersion of Co3O4, which afforded an optimum reducibility and acid site density.

N-Heptane isomerization on a new kind of micro/mesoporous catalyst: Pt supported on HZSM-5/HMS

Pt loaded on a series of ZSM-5/HMS composites with different H-zeolite amounts has been prepared and used as a solid acid catalyst for the catalytic isomerization of n-heptane. The structure characterization, acid distribution and morphology of the Pt catalysts supported on these composite materials were characterized by XRD, XRF, NH3-TPD, SEM, FTIR, Py-IR, H2 chemisorption, nitrogen sorption and TGA (for investigating the coke deposition) techniques. Compared with HMS and HZSM-5, these new composite materials have good ability for n-heptane isomerization. The results show that these micro/mesoporous catalysts have both properties of mesoporous HMS and microporous HZSM-5. The best i-C7 selectivity (35.8%) was observed for Pt/ZSM-5(30)-HMS at T=200°C. These new composite catalysts prove the catalytic stability at the reaction time, which results in their thicker pore-wall and appropriate acidity.

In-situ Synthesis and Catalytic Properties of ZSM-5/Rectorite Composites as Propylene Boosting Additive in Fluid Catalytic Cracking Process

Using rectorite extrudates from calcined rectorite powder as the starting material, a series of ZSM-5/rectorite composites were prepared via the in-situ crystallization method. The physicochemical properties and propylene boosting performance of the resulting samples were characterized by using X-ray diffraction, scanning electronic microscopy/energy dispersive spectrometer, N2 adsorption-desorption, and Fourier transformed infrared spectroscopy of pyridine adsorption, respectively, and assessed by using Daqing atmospheric residue as feedstock. The results showed that the ZSM-5/rectorite composites in which the ZSM-5 phase grows in-situ as a 2-3 ím thick layer on rectorite particles have a trimodal microporous-mesoporous-macroporous structure and thus exhibit outstanding propylene boosting performance. Compared with a commercial ZSM-5 incorporated fluid catalytic cracking catalyst, the ZSM-5/rectorite composite incorporated catalyst increased the yield and selectivity of propylene by 2.44% and 5.35%, respectively.

Organic template-free synthesis of ZSM-5/ZSM-11 co-crystalline zeolite

A series of ZSM-5/ZSM-11 co-crystalline zeolites with various compositions and morphologies were successfully synthesized via an organic template-free hydrothermal route and characterized by XRD, XRF, SEM, NMR and N 2 adsorption/desorption technologies. The effects of raw materials and batch composition were investigated systematically. Various silicon sources can be employed in the organic template-free synthesis of ZSM-5/ZSM-11 co-crystalline zeolite, however only a few types of aluminum sources are available. This organic template-free system is favorable to the aluminum-rich zeolite. With the increase of initial SiO 2/Al 2O 3 ratio, the ZSM-5 percentage in the ZSM-5/ZSM-11 co-crystalline zeolite increases as well as the crystal size, and especially the morphology of ZSM-5/ZSM-11 co-crystalline zeolite prepared from the colloidal silica–NaAlO 2 solution system changes gradually from nano-rod aggregation, micro-spindle to single hexagon and then to twinned hexagon crystals. Moreover, Na + and OH − in the initial materials can promote the nucleation of the ZSM-5/ZSM-11 co-crystalline zeolite significantly and are beneficial to the formation of crystals with relatively low length/width ratio, while K + postpones the crystallization process seriously.

Synthesis of ZSM-5 zeolite from rice husk ash: Characterization and implications for photocatalytic degradation catalysts

Silica synthesized from raw rise husks (white particles) through submission to consecutive chemical treatment using NaOH and HCl solutions was well incorporated with other components forming zeolites; under hydrothermal conditions, to synthesize two series of ZSM-5 (Z) of different Si/Al ratios, namely Z40 and Z80. Transition metal oxides (V, Co) were incorporated with Z samples by in situ synthesis and by impregnation. Various techniques were employed for samples characterization including XRD, FTIR, SEM, N 2 adsorption and pyridine-FTIR. The photocatalytic activity of V and Co incorporated Z zeolites in addition to neat ZSM-5 samples towards degradation of acid green (AG) dye were well investigated and compared under similar conditions. The characterization results of the catalysts indicated that Z80 measured higher surface area (616 m 2/g) and crystallites size (44.4 nm) than Z40 (536 m 2/g and 35.8 nm) besides, Z40 signifies the presence of distinct phase of silica capable of decreasing the pore radius and volume of this particular sample (22.9 Å, 0.49 cm 3/g) when compared with the former (25.3 Å, 0.623 cm 3/g). The degradation rate of Z40 was 16 times higher than Z80 in presence of UV irradiation reflecting the importance of absorbability of silica phase present on Z40 as well as acidity and decreased crystallites size. V and Co impregnated Z (VZ imp, CoZ imp) samples were found to exhibit higher and unique photocatalytic activities for AG degradation than in situ incorporated ones. CoZ80 imp exhibited the highest activity (0.14 min −1) among all samples exceeding CoZ40 imp (0.11 min −1) and VZ40 imp (0.043 min −1). The enhanced photocatalytic activity of CoZ80 imp is attributed to charge transfer excited complex between Co in Z along with AG ligand in addition to increasing the percentages of Co 3O 4 and cobalt silicate moieties over those in CoZ40 imp and to the higher surface area of CoZ80 imp, comparatively. More informations on local structures of metal oxides inside zeolites and their photocatalytic activities towards AG were deduced, correlated and discussed.

Skeletal isomerization of 1-pentene

Series of ZSM-5 and Y zeolite catalysts have been prepared. Zeolites were submitted to ion exchange, drying, formation with 50 wt.% of aluminium hydroxide as a binder and then to final thermal treatment. Determination of catalysts activity in 1-pentene isomerization reaction was carried out in the temperature range of 175–325°C. The highest activity in isomerization reaction was attained in the presence of ZSM-5 zeolite catalysts with strong and medium strength acidity.