Ratio Of ZSM-5 Research Articles

Jet fuel production via palm oil hydrodeoxygenation over bifunctional zeolite mixture supported Ni catalyst: Effect of Si/Al ratio

The influence of the Si/Al ratio of ZSM-5 on 10 wt% Ni/ZSM-5.SAPO-11 catalysts were investigated through the palm oil hydrodeoxygenation (HDO) process, based on the product selectivity of alternative jet fuel. This study utilizes a 1 L batch reactor at 60 bar and 350 °C for palm oil hydrodeoxygenation over 10 wt% Ni/ZSM-5.SAPO-11 catalysts. Si/Al ratio of 50 produces a 10 wt% Ni/ZSM-5.SAPO-11 catalyst with the optimum physicochemical properties for palm oil hydrodeoxygenation. TGA/DTG analysis of the spent catalyst shows that the catalyst has good thermal and catalyst stability with minor carbon deposition. GC/MS analysis also demonstrated a 100 % palm oil conversion to alternative jet fuel. The highest jet fuel yield of 51 % was attained with a Si/Al ratio of 50. The physicochemical properties of alternative jet fuel samples were measured to ensure that the conventional fuel standard limits were appropriately followed. These results indicated that such types of bifunctional Ni-based catalysts have the potential to be used in the conversion of triglycerides to alternative jet fuel.

Catalytic Cracking of Fischer-Tropsch Wax on Different Zeolite Catalysts

Fisher-Tropsch synthesis (FTS) is a promising method to make alternative hydrocarbons from biomass or other resources. Upgrading the primary FTS products is of considerable interest. Cracking FT wax is economically attractive to produce light olefins. Herein, the effects of the zeolite type, Si/Al ratio of ZSM-5, and reaction condition on the catalytic cracking of FT wax were investigated. It was found that the pore structure and acid properties of zeolites had a significant impact on the product selectivity. USY was beneficial for the production of gasoline and diesel, while β was suitable for the production of propylene and butenes, and ZSM-5 was conductive to producing ethylene and propylene. Increasing the Si/Al ratio of ZSM-5 can suppress the hydrogen transfer reaction and increase the selectivity of light olefins. When the Si/Al ratio of ZSM-5 was 140, the mass yields of ethylene, propylene, and butenes were 6.40%, 26.83%, and 20.10%, respectively.

Design of ZSM-5 encapsulating FeMnK nanocatalysts for light olefins synthesis with enhanced carbon utilization efficiency

Light olefins are important basic chemical materials, and the synthesis of light olefins from syngas via mild and efficient Fischer-Tropsch catalytic process is attractive. However, the application of technology is still plagued by the carbon utilization efficiency in CO conversion to target products. Therefore, both hydrocarbon distribution regulation and CO2 by-products reduction are desirable. Here, FeMnK oxide encapsulated by the hollow mesoporous ZSM-5 zeolite nanostructures with adjustable Si/Al ratio were constructed via a “dissolution-recrystalization” strategy, denoted as FeMnK@HM-Z-5(x), where x represents Si/Al ratio of ZSM-5 (x=∞, noted as FeMnK@HM-S-1). In catalytic performance, FeMnK@HM-Z-5(x) presented controlled regulation on hydrocarbon distribution and CO2 selectivity, compared with the supported or microporous coating structures, due to the distinct synergistic catalytic effect between FeMnK and ZSM-5. Carbon utilization efficiency reaches the maximum over FeMnK@HM-Z-5(200) with a space–time-yield of 22.7 μmol C2-C4∙gFe∙S-1 at similar CO conversion, due to the harmonization of light olefins selectivity improvement and CO2 suppression with the modulation of Si/Al ratio. With the aid of ethylene pulse experiment, C2H4-TPD, H2-TPD, in situ DRIFTS experiment, it confirmed that the change of light olefins and CO2 selectivity is mainly due to the variety of hydrogenation capacity, which is closely related to the Brønsted acid strength of the catalysts. CO2 pulse experiments further verified that the FeMnK@HM-Z-5(x) catalysts were endowed with different CO2 hydrogenation capacity. This study provides a new strategy for the precise regulation of the products distribution in CO / CO2 hydrogenation to enhance the carbon utilization.

Finely regulating methanol concentration to control the alkylation depth in methanol aromatization for optimizing product distribution

Uncontrollable alkylation in methanol to aromatics severely restricts the light aromatic selectivity and catalytic stability. Herein, we proposed a new strategy to control the alkylation depth by precisely regulating methanol concentration in alkylation environment. Firstly, the high Si/Al ratio ZSM-5 (HZ) was packed over Zn doped low Si/Al ratio ZSM-5 (Zn/LZ) to form dual bed to inhibit deep alkylation for high catalytic stability and BTX selectivity. Secondly, part of methanol was introduced into lower Zn/LZ bed to promote methyl-cyclopentene alkylation for aromatic production and product optimization. After such regulation, toluene selectivity in aromatics decreased from 27.9% to 20.8% accompanied by an increase in xylene selectivity from 37.1% to 44.0%. BTX selectivity in aromatics also improved to 66.7% with 97.5 h of catalyst lifetime, much higher than 50.0% and 20 h of the single Zn/LZ bed. This work realized stable light aromatic production from methanol by controlling the microscopic reaction routes.

Strengthening catalytic synergy of two function-complementary ZSM-5 by optimizing their spatial organizations in fixed-bed reactor to boost methanol aromatization

The effect of proximity of two different SiO 2 /Al 2 O 3 ratio ZSM-5 catalysts with complementary acidic properties on their catalytic synergy over methanol stepwise aromatization was specifically studied based on a series of different packing modes. The results showed that the powder mixing mode with high proximity excessively enhanced the synergy by intensifying mass transfer between two catalysts. Although it presented a high aromatics selectivity of 57.2%, but the catalyst lifetime was only 10 h due to the intense reverse of polymethylbenzene. The granule mixing mode with larger particle size only slightly improved the catalyst lifetime. Packing two ZSM-5 catalysts in separated dual beds mode could prolong the lifetime to 157 h but the aromatics selectivity was reduced to 21.0%, indicating that low proximity is not favored the catalytic synergy. Interestingly, the suitable proximity of designed alternative sequence beds mode not only intensified intermediates transport to some extent but also relieved the negative influence of aromatic reversion. The moderate synergy remarkably increased the aromatics selectivity to 28.9% with a satisfactory lifetime of 117 h. This work preliminarily elucidates the effect of proximity determined by the spatial organization of double ZSM-5 catalysts on their catalytic synergy for methanol aromatization. Packing Zn/Z-60 and NZ-500 in alternating sequence beds (packing mode) in the tubular fixed bed observably prolonged catalytic lifetime with a satisfied aromatics selectivity. • The effect of proximity on catalytic synergy of double ZSM-5 for MTA was studied. • The catalyst proximity was precisely regulated based on eight packing modes. • Enhanced mass transfer for aromatization was achieved under high proximity. • Catalytic stability was increased by decreasing catalyst proximity. • Mild catalyst proximity over alternate beds enhanced catalytic synergy for MTA.

Effect of ZSM-5 zeolite porosity on catalytic cracking of n-heptane

The selectivity of ethylene and propylene in cracking of n-heptane is connected to the micropore to mesopore ratioof ZSM-5 structure.

Microwave pyrolysis characteristics and product of Chlorella vulgaris under compound additives and optimization by Box-Behnken design

Microwave-assisted pyrolysis of Chlorella vulgaris was carried out under compound additives, which contained catalyst (ZSM-5) and microwave absorbent (graphite). The effects of three independent variables (Si/Al ratio of ZSM-5, additives amount and catalyst ratio) on the weight loss characteristics, product yield and energy consumption were investigated. Response Surface Methodology (RSM) coupled with Box-Behnken Design (BBD) was used to optimize pyrolysis time (Ts) and bio-oil yield (Bo) of Chlorella vulgaris pyrolysis under three independent variables. The results showed that compound additives can promoted the pyrolysis progress and increased the bio-oil yield. Besides, compound additives can also reduce the energy consumption of bio-oil production in most cases. The predicted results showed that optimal Ts and Bo were 3550s and 22.70%, respectively. GC-MS analysis further revealed that compound additive has stronger effect on denitrogenating than single additive, which is of great significance in alleviating nitrogen oxide pollution caused by bio-oil with high nitrogen content.

Improved protocol for optimizing Mo/ZSM-5 catalyst for methane aromatization

A systematic DoE approach is developed to optimize Mo-based ZSM-5 catalyst recipe for methane dehydro-aromatization process. Aim is to achieve maximum benzene productivity with improve catalyst stability. Three major factors - Si/Al ratio of ZSM-5, pH of Mo incorporation and catalyst activation along with two different responses - benzene yield and final/peak methane conversion (or in other words the extent of catalyst stability) were considered for constructing the DoE. The benzene yield and final/peak methane conversion vary significantly depending on the catalyst recipe including the catalyst activation protocol/conditions. The combination of Si/Al ratio of 15, pH of Mo incorporation 10 and control catalyst activation by pre-carburization identified through DoE helped to achieve maximum/optimum benzene yield and the catalyst stability. Moderate acidity of zeolite, high Mo dispersion and presence of higher quantity of catalytically active Mo-carbide/oxycarbide species seems to be the reason for high benzene productivity and catalyst stability.

Catalytic synergy between the low Si/Al ratio Zn/ZSM-5 and high Si/Al ratio HZSM-5 for high-performance methanol conversion to aromatics

Rational mixing of two kinds of catalysts with catalytic coupling functions could efficiently convert reactants to products via two successive steps. Herein, high Si/Al ratio ZSM-5 (Z220) was mixed with low Si/Al ratio Zn/ZSM-5 (ZnZ30) for two-step methanol conversion to aromatics (MTA). Sufficient experiments explored their catalytic synergy and found that methanol was firstly converted into light hydrocarbons on Z220, and then light hydrocarbons were converted into aromatics on neighboring ZnZ30. ZnZ30 not only catalyzed light alkenes into aromatics, but also catalyzed light alkanes to light alkenes and then to aromatics. Changing mixing ratio controlled the proportions of two steps for MTA reaction and achieved a good match between two processes, which increased aromatic selectivity from 30.3%–39.9% and prolonged lifetime by a factor of 10 compared with one-step aromatization. Optimizing reaction temperature, Si/Al ratio and granule size of catalysts further strengthened their catalytic synergy for improved catalytic performance.

Hydrophobic nano-layer on surface prevents H2O adsorption in moderately aluminum deficient Y zeolite crystals

Abstract Experimental and computer simulation sorption and spectroscopic studies were evaluated in-order to be able to answer two puzzling questions. (1) How can a Si/Al ~40 ratio commercial H+ exchanged Y zeolite (H–Y), CBV 780, adsorb only nearly as little H2O as a Si/Al ~ 4330 ratio ZSM-5? (2) Why another Si/Al ~ 40 ratio commercial H–Y, CBV 901, adsorbs much less H2O than CBV 780 and even less than the mentioned highly siliceous ZSM-5? These zeolites have not been chemically treated to be hydrophobic, only their patented synthesis and post-treatment conditions differ. Results indicate that the crystallites of CBV 901 are covered with a defect and aluminum free siliceous nano-layer, which prevents any H2O penetration into the bulk. The external surface of CBV 780 crystallites has about the same little amount of Al as its bulk, presumably less than 4 Al per unit cell. Due to the low number of Al-associated Bronsted acidic hydroxyls (BA-OH), on which H2O preferably adsorbs, little water adsorption takes place in the micropores. On the other hand the surface of the large mesopore defects of CBV 780 must be enriched in with Al to get the measured overall Si/Al ~40 ratio in this material, which provides enough BA-OH sites for adsorbing H2O molecules as a prelude to mesopore filling, that manifests itself in a Type II sorption isotherm.

The selective and stable synthesis of aromatics from methanol via two-step route using light alkenes as intermediates

As a potential non-petroleum route for the synthesis of aromatics, it is still difficult to obtain high catalytic stability and aromatic selectivity in traditional one-step methanol conversion over traditional low Si/Al ratio ZSM-5. In this work, high Si/Al ratio (220) ZSM-5 was packed above Zn doped low Si/Al ratio (30) ZSM-5 and the obtained catalyst bed was used to convert methanol into aromatics. Based on series of comparative experiments on catalyst packing modes, it was found that over upstream high Si/Al ratio ZSM-5, methanol was mainly converted into light alkenes, especially propene and butene. Then, these light alkenes were further converted into aromatics over downstream Zn doped low Si/Al ratio ZSM-5. The catalytic lifetime was tenfold longer than that of one-step conversion for the native long lifetime of upstream catalyst and the facilitated alkene-based cycle over downstream catalyst, which suppressed the coke formation. The decreased reaction depth of aromatic-based cycle promoted the BTX (benzene, toluene and xylene) formation and BTX selectivity in aromatics reached 71.7% for this two-step conversions using light alkenes as intermediates, much higher than 51.2% of one-step conversion. Regulating the packing ratio of above two catalysts optimized the coupling efficiency of two corresponding reactions, and aromatic selectivity in total hydrocarbons increased from 26.7% to 48.2%. Given the unchanged BTX selectivity in aromatics, BTX selectivity in total hydrocarbons increased from 19.1% to 34.8% and was much higher than that of one-step conversion (15.5%). This work offers a prospective route for the selective and stable synthesis of aromatics from methanol.

Extrusion and Characterization of High Si/Al Ratio ZSM-5 Using Silica Binder

Biogas upgrading is a key operation for transforming raw biogas into valuable biomethane that can be used as fuel or transported through pipelines. Pressure swing adsorption (PSA) is one possible technique that can be used for upgrading. ZSM-5 with high silica/aluminum (Si/Al) ratio has a reasonable CO2/CH4 selectivity and an almost linear CO2 adsorption isotherm, which can reduce power consumption. Extrusion of zeolites uses Al-based binders which can result in a denaturation and in a decrease of Si/Al ratio, promoting a steeper CO2 isotherm and also impacting the water adsorption. In this work, we have extruded a ZSM-5 (with a Si/Al = 200) using only silica-based binder. Different samples were obtained using different extrusion paste compositions and operating conditions and their textural properties characterized. The mechanical strength of the samples as well as the CO2, CH4, and H2O adsorption equilibrium isotherms at 303–343 K were measured. Our results show that it is possible to produce extrudates with mechanical resistance comparable to (or higher than) commercial zeolite materials with surface area reductions lower than 10% and little or no impact on the CO2/CH4 selectivity.

Synthesis and Characterization of ZSM-5 Zeolite from Dealuminated and Fragmentated Bayat-Klaten Natural Zeolite

Synthesis of ZSM-5 zeolite was conducted using natural zeolite of Bayat-Klaten by employing fragmentation method of sub-molten system through breaking zeolite framework into its monomer in alkaline condition at 250°C. Prior to fragmentation, one part of zeolite was treated with dealumination and the other one without dealumination, labeled as ZSM-5_a and ZSM-5_wa, respectively. Characterization with FTIR, XRD, and EDX showed that the fragmentation was successful, in which the structure of zeolite was damaged and the infrared bands due to AlO4 and SiO4 were appeared. The synthesis of ZSM-5 was performed hydrothermally using tetrapropylammonium hydroxide (TPAOH) as a directing agent of pore structure and addition of LUDOX (40% silica suspension in water). The XRD characterization showed the as synthesized materials had the structure of ZSM-5 zeolites with high crystallinity. Imaging with SEM showed the characteristic of hexagonal ZSM-5 crystals. The BET surface area analysis showed a typical surface area of microporous zeolite, 262 m2/g, and pore diameter of 1.496 nm; indicating that the ZSM-5 zeolite obtained was micropore size. The Si/Al ratio of ZSM-5_a and ZSM-5_wa were 18 and 21, respectively. These results indicated that Bayat-Klaten natural zeolite can be used as silica and alumina source for high crystalline ZSM-5 with medium Si/Al ratio and having good thermal stability. Thus, these materials are potential to be tested as fluid hydrocracking catalyst.

Synthesis, characterization and evaluations of the Ag/ZSM-5 for ethylene oxidation at room temperature: Investigating the effect of water and deactivation

Ag/ZSM-5 catalysts with different SiO2/Al2O3 ratios were prepared and evaluated for ethylene oxidation at 25 °C. Ethylene can be completely oxidized into CO2 by all the Ag/ZSM-5 catalysts at 25 °C. It is found that SiO2/Al2O3 ratio of ZSM-5 has a significant effect on catalytic stability. Ag/ZSM-5 with SiO2/Al2O3 ratio of 38 exhibits enhanced catalytic stability compared with other Ag/ZSM-5 catalysts. The conversion of ethylene with Ag/ZSM-5 (SiO2/Al2O3 = 38) remained approximately 100% for 405 min at 25 °C, and then the ethylene conversion gradually decreased to zero in the following 450 min. It is revealed that Brønsted acid sites are the C2H4 adsorption sites and the inhibition of C2H4 adsorption sites by H2O vapor is one of the crucial reasons of the activity loss for ethylene oxidation. H2O adsorption-desorption kinetics results demonstrate that slow adsorption and fast desorption characters of H2O on Ag/ZSM-5 with SiO2/Al2O3 ratio of 38 contribute to its good catalytic stability for ethylene oxidation. Taking into account the elucidation of the negative effect of H2O adsorption on Brønsted acid sites on the catalytic stability of Ag/ZSM-5 catalysts for ethylene oxidation, this work will provide new insights into designing high-performance catalysts for ethylene elimination at room temperature.

Depolymerization of Protobind lignin to produce monoaromatic compounds over Cu/ZSM-5 catalyst in supercritical ethanol

The depolymerization reaction of Protobind lignin (PL) was conducted over metal supported on ZSM-5 catalysts in supercritical ethanol without supplying additional hydrogen in order to obtain the high yield of monoaromatic compounds. The reaction was performed by changing the various variables of catalyst such as the types of transition metals (Co, Ni and Cu), the amount of metal loading (5wt.%, 10wt.% and 30wt.% of Cu) and the Si/Al2 ratio of ZSM-5 (30, 50, 80 and 200). Cu/ZSM-5 displayed the highest yield of monoaromatic compounds among the transition metals. When it comes to the Si/Al2 ratio of Cu/ZSM-5, 10wt.% Cu/ZSM-5 with Si/Al2 of 30 demonstrated the highest yield (98.2wt.%) of monoaromatic compounds. Moreover, the linear correlation between yield of monoaromatic compound and acid density of Cu/ZSM-5 was identified. Meanwhile, HSQC NMR analysis provided the evidence about the promotion of the depolymerization of Protobind lignin via hydrogenolysis. In addition, some products such as ethylated compounds were confirmed by HSQC NMR spectra resulting from the alkylation between monoaromatic compounds and ethanol. It was also found that Cu metal plays a promotional role in enhancing the lignin depolymerization.

P-Xylene selectivity enhancement in methanol toluene alkylation by separation of catalysis function and shape-selective function

Catalyst reactivity and selectivity always compromise with each other in most reactions. HZSM-5 catalyst for the methanol toluene alkylation reaction suffers from active site loss when modified by elements such as Si, P, Mg and B to attain high p-xylene selectivity, incurring problems of low toluene conversion and rapid catalyst deactivation. In the present study, the separation of catalysis function and shape-selective function was achieved by epitaxial growing a Silicate-1 layer over HZSM-5 crystal to create an HZSM-5@S-1 catalyst. HZSM-5@S-1 was shown to possess less weak acid sites but more strong acid sites than the parent HZSM-5. With reduced contact time, the catalyst showed increased p-xylene selectivity up to 88% but no obvious degradation in toluene conversion. The enhancement of Silicate-1 shell to PX selectivity was less effective when applied to low Si/Al ratio ZSM-5 samples, due to the re-incorporation of aluminium leached from low Si/Al ratio parental ZSM-5 samples into the newly formed Silicate-1 framework. Benefiting from retaining most of the strong acid sites of HZSM-5, the catalyst showed high toluene conversion with increasing WHSV without apparent deactivation over a 130hours service life test.

Controllable synthesis of composites of ZSM-5 and KIT-1 using an ionic liquid as template

ZSM-5/KIT-1 composites were synthesized using an ionic liquid as a template. The structures and morphologies of as-obtained products were characterized using an infrared spectroscopy, X-ray diffractometer, N2 adsorption/desorption, scanning electron microscopy and transmission electron microscopy. The resultant zeolites show a fully crystalline microporous MFI zeolite framework and a three-dimensional network of short worm-like channels. Mesopores and microspores of 4.2 and 0.8 nm in diameter coexist in the zeolite composites. Moreover, the ratio of ZSM-5 and KIT-1 could be simply adjusted by controlling the pre-crystalline time. We believe that the strategy for fabricating ZSM-5/KIT-1 through a simple method could potentially promote the large-scale production of zeolite composites.

Selective conversion of organic pollutant p-chlorophenol to formic acid using zeolite Fenton catalyst

Effective remediation technologies which can converse the harmful organic pollutants to high-value chemicals are crucial both for wastewater treatment and energy regeneration. This study provides an evidence that extracting useful chemicals from wastewater is feasible through selective conversion of p-chlorophenol to high value formic acid as an example. The reported system works with a readily available Fe-containing ZSM-5 catalyst, water as the solvent and hydrogen peroxide as the oxidant. The yield of formic acid reached up to 50.7% when the Si/Al ratio of ZSM-5 was 80 and the Fe-content was 1.4%. By X-ray adsorption fine structure (XAFS), NH3 temperature-programmed desorption (NH3-TPD) technique, the pyridine adsorption Fourier-transition infrared (Py-IR) spectroscopy and adsorption measurements, it was concluded that the controllable degradation of p-CP could be approached through selective adsorption, the moderate Brønsted acid sites for H2O2 activation and the properly selective conversion control due to extra-framework coordination unsaturated sites (CUS) of Fe. This approach might provide a new avenue for the field of organic pollutant remediation.

Methylbenzene hydrocarbon pool in methanol-to-olefins conversion over zeolite H-ZSM-5

The formation and reactivity of a methylbenzenes (MBs) hydrocarbon pool in the induction period of the methanol-to-olefins (MTO) reaction over zeolite H-ZSM-5 was investigated and the mechanistic link of MBs to ethene and propene was revealed. Time evolution analysis of the formed MBs and 12C/13C methanol-switching experiments indicate that in the induction period bulkier compounds such as tetraMB and pentaMB have higher reactivity than their lighter counterparts such as p/m-diMB and triMB. By correlating the distribution of MBs trapped on H-ZSM-5 with ethene and propene, we found that tetraMB and pentaMB favor the formation of propene, while p/m-diMB and triMB mainly contribute to the formation of ethene. On the basis of this relationship, the olefin (ethene and propene) selectivity can be controlled by regulating the distribution of trapped MBs by varying the silicon-to-aluminum ratio of ZSM-5, reaction temperature, and space velocity. The reactivity of MBs and the correlation of MBs with olefins were also verified under steady-state conditions. By observation of key cyclopentenyl and pentamethylbenzenium cation intermediates using in situ solid-state NMR spectroscopy, a paring mechanism was proposed to link MBs with ethene and propene. P/M-diMB and triMB produce ethylcyclopentenyl cations followed by splitting off of ethene, while tetraMB and pentaMB generate propyl-attached intermediates, which eventually produce propene. This work provides new insight into the MBs hydrocarbon pool in MTO chemistry.

금속담지 ZSM-5 촉매를 사용한 에탄올로부터 방향족 화합물 제조에 관한 제올라이트의 금속성분 및 실리카/알루미나 비의 영향

고정층 반응기를 사용하여 상압에서 에탄올로부터 방향족화합물 제조에 관한 ZSM-5 제올라이트의 금속성분 및 실리카/알루미나 비의 영향을 고찰하였으며, 반응온도, 중량공간속도(WHSV), 반응물인 에탄올에 물 및 메탄올 첨가 영향도 검토하였다. 촉매로는 Si/<TEX>$Al_2$</TEX> 비율이 23~280 범위의 상용 ZSM-5에 Zn, La, Cu, Ga 성분을 함침시켜 촉매 활성 및 안전성 테스트에 사용하였다. 촉매의 특성분석을 위해 암모니아 승온탈착 실험(<TEX>$NH_3$</TEX>-TPD)과 질소 흡-탈착실험을 수행하였다. 실험결과, 방향족화합물의 선택도에 관한 ZSM-5에 함침한 금속성분과 ZSM-5의 Si/<TEX>$Al_2$</TEX>비에 크게 영향을 받았는데, 함침금속은 Zn-La > Zn > La > Cu > Ga 순으로 감소하였으며, ZSM-5의 적절한 산점을 가진 Si/<TEX>$Al_2$</TEX>=50, 80에서 가장 우수하였다. 최적 반응온도(<TEX>$437^{\circ}C$</TEX>)와 공간속도(<TEX>$0.8h^{-1}$</TEX>)에서 방향족화합물의 선택도는 초기 72%에서 30시간 이후 56%로 서서히 감소하는 경향을 나타내었다. The catalytic conversion of ethanol to aromatic compounds ETA was studied over ZSM-5 heterogeneous catalysts. The effect of reaction temperature, weight hourly space velocity (WHSV), and addition of water and methanol, which are the potential impurities of bio-ethanol, on the catalytic performance was investigated in a fixed bed reactor. Commercial ZSM-5 catalysts having different Si/<TEX>$Al_2$</TEX> ratios of 23 to 280 and modified ZSM-5 catalysts by addition of metal (Zn, La, Cu, and Ga) were used for the activity and stability tests in ETA reaction. The catalysts were characterized with ammonia temperature programmed desorption (<TEX>$NH_3$</TEX>-TPD) and nitrogen adsorption-desorption techniques. The results of catalytic performance revealed that the optimal Si/<TEX>$Al_2$</TEX> ratio of ZSM-5 is about 50~80 and the selectivity to aromatic compounds decreases in the order of Zn/La > Zn > La > Cu > Ga for the modified ZSM-5 catalysts. Among these catalysts from the ETA reaction, Zn-La/ZSM-5 showed the best catalytic performance for the ETA reaction. The selectivity to aromatic compounds was 72% initially and 56% after 30 h over the catalysts at reaction temperature of <TEX>$437^{\circ}C$</TEX> and WHSV of <TEX>$0.8h^{-1}$</TEX>.