Modified HZSM-5 Zeolite Catalysts Research Articles

Bimetallic Lanthanum-Cerium-Loaded HZSM-5 Composite for Catalytic Deoxygenation of Microalgae-Hydrolyzed Oil into Green Hydrocarbon Fuels.

Due to their high lipid content, microalgae are one of the most significant sources of green hydrocarbons, which might help lessen the world's need for fossil fuels. Many zeolite-based catalysts are quickly deactivated by coke production and have a short lifetime. In this study, a bimetallic Lanthanum-Cerium (La-Ce)-modified HZSM-5 zeolite catalyst was synthesized through an impregnation method and was tested for the conversion of hydrolyzed oil into oxygen-free hydrocarbon fuels of high energy content. Initially, hydrolyzed oil (HO), the byproduct of the transesterification process, was obtained by the reaction of crude oil derived from Chlorella vulgaris microalgae and a methanol. Various catalysts were produced, screened, and evaluated for their ability to convert algal HO into hydrocarbons and other valuable compounds in a batch reactor. The performance of HZSM-5 was systematically tested in view of La-Ce loaded on conversion, yield, and selectivity. NH3-TPD analysis showed that the total acidity of the La-Ce-modified zeolites was lower than that of the pure HZSM-5 catalyst. TGA testing revealed that including the rare earth elements La and Ce in the HZSM-5 catalyst lowered the catalyst propensity for producing coke deposits. The acid sites necessary for algal HO conversion were improved by putting La and Ce into HZSM-5 zeolite at various loading percentages. The maximum hydrocarbon yield (42.963%), the highest HHV (34.362 MJ/Kg), and the highest DOD% (62.191%) were all achieved by the (7.5%La-2.5%Ce)/HZSM-5 catalyst, which was synthesized in this work. For comparison, the hydrocarbon yield for the parent HZSM-5 was 21.838%, the HHV was (33.230 MJ/Kg), and the DOD% was 44.235%. In conclusion, La and Ce-loading on the parent HZSM-5 may be responsible for the observed alterations in textural properties; nevertheless, there is no clear correlation between the physical features and the hydrocarbon yield (%). The principal effect of La and Ce modifying the parent HZSM-5 zeolite was to modify the acidic sites needed to enhance the conversion (%) of the algal HO during the catalytic deoxygenation process, which in turn raised the hydrocarbon yield (%) and increased the HHV and DOD%.

Catalytic Performance of Phosphorus Modified HZSM-5 Zeolite Catalysts in the Co-cracking Reaction of n-Hexane and Methanol

Catalytic Performance of Phosphorus Modified HZSM-5 Zeolite Catalysts in the Co-cracking Reaction of n-Hexane and Methanol

Microalgae biomass conversion into biofuel using modified HZSM-5 zeolite catalyst: A review

Microalgae is one of the most important sources of green hydrocarbons and it is likely to reduce dependence on fossil fuels due to the high percentage fats of microalgae, and also has a rapid growth rate and consumes the carbon dioxide in large quantities. Besides, the cultivation of microalgae does not require arable land. This short review aims to explain the suitability of microalgae as a biofuel source depending on the content of lipids, and catalytic chemical processes to convert the crude oil of microalgae into biofuels by using different types of modified HZSM-5 zeolites. Also, this review sheds light on the different methods to modify HZSM-5 zeolite toward enhancing the selectivity of cracking and deoxygenation processes by using modified HZSM-5 zeolite with rare earth metals.

Enhanced Light Olefin Production in Chloromethane Coupling over Mg/Ca Modified Durable HZSM-5 Catalyst

A series of Mg/Ca modified HZSM-5 zeolite catalysts were prepared by the impregnation method for catalytic coupling of CH3Cl to light olefins. The catalysts were characterized using X-ray diffracti...

Kinetic study of alkylation of benzene with ethanol over bimetallic modified HZSM-5 zeolite catalyst and effects of percentage metal loading

Alkylation of benzene with ethanol was analyzed using shape selective boron–magnesium bimetallic HZSM-5 (Si/Al = 90) zeolite catalyst. The alkylation of benzene with ethanol (2:1 by volume) produces ethylbenzene as primary product and others like 1, 2-Diethylbenzene, 1, 4-Diethylbenzene, and xylene mixtures as secondary products. The physiochemical properties of catalyst were characterized by XRD, BET, TGA, FTIR, NH3-TPD, and FE-SEM. The feed and products were analyzed by gas chromatography and mass spectroscopy. B–Mg bimetallic catalysts supported on HZSM-5 zeolite catalyst with SAR = 90 were synthesized by the incipient wetness impregnation method and examined for alkylation of benzene with ethanol. Total metal loading of 5, 10, and 15% was used for catalyst synthesis. The highest selectivity of ethylbenzene (76.22%) was obtained by (Mg + B)-15%-HZSM-5 and the lowest ethylbenzene selectivity (49.15%) was obtained by (Mg + B)-5%-HZSM-5 using 2:1 benzene-to-ethanol ratio by volume. A reaction scheme with three parallel routes leading to the formation of ethylbenzene, diethylbenzene, and triethylbenzene was considered for the kinetic study. The kinetic parameters were determined using Langmuir–Hinshelwood–Hougen–Watson (LHHW)-type kinetic model. LHHW model could satisfactorily correlate the rate data and this model gives good fit between the experimental and calculated data.

Remarkably enhanced stability of HZSM-5 zeolite co-modified with alkaline and phosphorous for the selective conversion of bio-ethanol to propylene

The effects of alkaline, phosphorous and dual alkaline-phosphorous modifications on the selective conversion of bio-ethanol to propylene over HZSM-5 zeolite catalysts were investigated. The results demonstrate that the doubly modified HZSM-5 zeolite catalyst offers higher propylene selectivity and remarkably improved catalytic stability than the parent and singly modified counterparts, which can be contributed to the formation of new mesoporous and decreased amount of strong acid sites induced by the alkaline treatment and phosphorous modification, respectively. The deactivation of the phosphorous and dual alkaline-phosphorous modified HZSM-5 zeolite catalysts was caused by carbon deposition but not by dealumination, which can be attributed to the enhanced hydrothermal stability of the framework aluminum by the modification of ZSM-5 zeolite with phosphorus.

Alkylation of benzene with ethanol over modified HZSM-5 zeolite catalysts

Alkylation of benzene with ethanol was analysed using unmodified as well as modified shape selective HZSM-5 (Si/Al = 31) zeolite catalysts. The reaction was carried out in a continuous fixed bed flow reactor in the temperature range of 300–500 °C at atmospheric pressure to investigate the activity of various catalysts for the selectivity and yield of ethylbenzene (the desired product). The alkylation of benzene with ethanol (2:1 by volume) produces ethyl benzene as primary product and others like diethylbenzene, triethylbenzene and xylene mixtures as secondary products. The modification of HZSM-5 was done by impregnation using boron and magnesium. The modification caused changes in the surface area, acidity and pore volume of zeolite sample. The physiochemical properties of catalysts were characterised by XRD, TEM, BET, TGA, FTIR, NH3-TPD and SEM. The feed and products were analysed by gas chromatography. The conversion of benzene was found to be better in bi metallic (B and Mg) modified HZSM-5 followed by unmodified HZSM-5. The modified catalysts gave better selectivity (72.8 %) and yield (38.1 %) of ethylbenzene.

The Effect of Hydrothermal Treatment on the Aromatization Performance of HZSM-5 Modified by Zn, P

Zn and P modified HZSM-5 zeolite catalysts were prepared by impregnation method using HZSM-5 zeolite prior to hydrothermal treatment. The surface area, the acid center style, and the acid strong distributing on hydrothermal treatment HZSM-5 zeolite were characterized by XRD, BET, NH3-TPD, and FT-IR techniques. Meanwhile, the influence of hydrothermal treatment temperature on the aromatization performance of the catalyst was investigated using FCC gasoline (50–100°C fraction) as feedstock. The result showed that, along with the temperature of hydrothermal treatment heightening, the surface area reduced and pore volume increased a little, however, the pore size clearly increased; at the same time the total acid amount and the number of strong acid sites of HZSM-5 were reduced significantly. With the hydrothermal treatment temperature increasing, the catalyst initial activity gradually decreased and the stability presented the trend of first increase then decrease. The HZSM-5, which was treated by hydrothermal at 550°C modified by zinc and phosphor, exhibited preferable aromatization performance. After reacting 16 h, the conversion of olefins, the contents of aromatic, and the yield of liquid products were 90.26, 54.06, and 10.02%, respectively.

Intensifying Propylene Production by 1-Butene Transformation on a K Modified HZSM-5 Zeolite-Catalyst

The effect operating conditions have in the selective transformation of 1-butene into propylene has been studied on a catalyst of HZSM-5 zeolite (SiO2/Al2O3 = 280) modified with 1 wt % K (of moderate acid strength) and agglomerated with bentonite and alumina. The kinetic runs have been performed in a fixed bed reactor under the following operating conditions: 400–600 °C; space time, up to 1.6 (gcatalyst·h) (molC)−1; and butene partial pressure, 0.375–1.35 bar. The kinetic performance has been evaluated at zero time and throughout time on stream in order to find the suitable conditions to maximize propylene yield and selectivity and minimize deactivation by coke. A region of optimum propylene yield (>30%) and propylene selectivity (>50%) has been established for temperatures above 500 °C and space time values depending on the reaction temperature. Furthermore, cofeeding 50% of inert gas is highly recommended in order to attenuate coke deactivation.

Preparation of Phosphorus Modified HZSM-5 Zeolite Catalysts and their Catalytic Performances of Methanol to Olefins

To improve the selectivity of light olefins, Phosphorous modified ZSM-5 zeolites catalysts with different phosphorous content were prepared by impregnation and were used in the conversion of methanol to olefins. The properties of acidity and microporous structure of the phosphorous modified ZSM-5 zeolites were investigated by XRD, N2-adsorption and desorption, and NH3-TPD. The highest propylene yield (50.82%) was observed over the H-ZSM-5 modified with the phosphorus content at 9% (weight percent). The selectivity of propylene depended strongly on the phosphorus content in the zeolites; The enhancement of propylene selectivity with increasing phosphorous content was attributed to reduction of strong acid sites on the H-ZSM-5. Modification of the ZSM-5 zeolites with phosphorous also changes the microporous structure.