Catalytic Dehydration Of Ethanol Research Articles

Reduction of the Hydrogen Content of CO2 Methanation Product Gas via Catalytic Ethanol Dehydration–Hydrogenation

Reduction of the Hydrogen Content of CO2 Methanation Product Gas via Catalytic Ethanol Dehydration–Hydrogenation

Integrated syngas biorefinery for manufacturing ethylene, acetic acid and vinyl acetate

The paper presents the design of an innovative process for manufacturing sustainable biochemicals, as acetic acid, ethylene and vinyl acetate monomer (VAM), in an integrated syngas biorefinery using renewable feedstock as biomethane and captured CO2. The work is supported by full design and simulation of six plants imbedded in a large process: syngas1H2/CO 2:1 by catalytic partial oxidation of methane, syngas2 H2/CO 1:1 by dry methane reforming, methanol, acetic acid by carbonylation, ethylene and vinyl acetate. A key contribution is the development of a novel acetic-acid-to-ethylene process starting from syngas. This consists of catalytic hydrogenation of acetic acid (exothermic) followed by catalytic ethanol dehydration (endothermic). The thermal integration of reactors leads to low energy process and superior sustainability measures versus petrochemical and methanol-to-olefin processes. The comprehensive simulation of the integrated biorefinery allows getting consistent mass and energy balances, performing energy analysis and capital cost estimation, and finally delivering reliable sustainability measures. Based on syngas the carbon-yield, mass-yield, carbon footprint (kg CO2/kg product) and energetic requirement (MJ/kg) are 78.6 %, 34.7 %, 1.6 % and 11.2 % for ethylene, and 80.8 %, 46.8 %, 1.5 % and 11.9 % for VAM. At high biomethane price the ethylene may be costly but manufacturing the higher value VAM is fully profitable.

Simultaneous catalytic dehydration of methanol and ethanol: How ZSM-5 acidity addresses conversion and products distribution

The sustainable chemistry based on acid-catalysed alcohol conversion reaction is a promising route to contribute to the de-fossilization strategies completion. In this concern, C1 and C2 alcohols are both well recognised sources for the production of ethers and olefins from sustainable sources in acid catalysed dehydration reaction pathway. Most of the literature is devoted to the investigation of pure alcohols conversion, whilst the simultaneous dehydration of alcohol in mixture can broad the product panel (contributing to the enlargement of bio-alcohols based chemistry) also elucidating the role of acidity (type and distribution) on the reaction mechanism. This paper is the first contribution analysing the role of acid sites (amount and distribution) on the simultaneous methanol/ethanol dehydration using ZSM-5 zeolites. ZSM-5 materials with different aluminium content were synthesised and used in catalytic test. The obtained results showed how Lewis acid sites are less important when dealing with ethanol (also in mixture with methanol) and how the different methylated- ethylated species formation can affect the product composition and the coke amount and composition.

Elucidation on supporting effect of WO3 over MCF-Si and SBA-15 catalysts toward ethanol dehydration

BackgroundThe alternative conversion of ethanol into valuable products, such as ethylene, through catalytic ethanol dehydration becomes highly appealing due to the surplus of ethanol. This research aims to investigate the catalytic activity of WO3 on SBA-15 and mesocellular form silica (MCF-Si), which have been prepared using different methods and utilized as catalysts in ethanol dehydration. MethodsWO3 was impregnated on the SBA-15 and MCF-Si supports using two different methods, including incipient wetness (IW) and wetness impregnation (W). All catalysts were tested in the vapor phase of ethanol dehydration at reaction temperatures ranging from 200 to 400 °C and were characterized by powerful techniques. Significant findingsThe findings revealed that the three-dimensional mesocellular foam structure of MCF-Si and the incipient wetness impregnation of WO3 are the keys to obtaining a highly dispersed WO3 catalyst with suitable acid properties. Additionally, the high Lewis to Bronsted (L/B) ratio of tungsten on silica is crucial for the catalytic dehydration of ethanol to ethylene. Among all catalysts, the WO3/MCF-Si (IW) exhibited the highest ethylene yield (98.3%), having an ethanol conversion of 99.6% and an ethylene selectivity of 98.7% at 400 ºC.

Modelling and control of a bio-ethylene production process

Ethylene is one of the most consumed products in the world, as it has many uses such as the production of nylon from its polymeric compound, the production of vinyl chloride, which is polymerized to polyvinyl chloride for the production of plastics, the production of ethylene oxide, used as a ripening agent for fruits, etc. The conventional method adopted in the production of ethylene is by steam cracking of naphtha at high temperatures. Naphtha is a hydrocarbon, so when cracked, it releases harmful carbon dioxide (CO2) into the atmosphere, and this brought about looking for alternative methods of producing ethylene. As discovered, ethylene can be produced by catalytic dehydration of ethanol, but the main limitation of this process is that the purity of ethylene produced by this approach may not be up to the desired polymer grade of 99.97%. As such, this work has been carried out to model, with the aid of Aspen Plus, and develop control techniques that would enable the process to meet up with the desired output maximum purity from the distillation column (100% ethylene at the top product of the distillation column). In line with that, P-only, PI, and PID controllers tuned with the Tyreus-Luyben technique, Zeiger-Nichols method, and a modified Tyreus-Luyben approach have been used for the control of this process. It was discovered that the PID controller tuned with the modified Tyreus-Luyben parameter had the lowest Integral Absolute Error (IAE) of 1.474 and Integral Time Absolute Error (ITAE) of 4.767 and, hence, it was found out that it could be adopted for proper control of this process, although limited to small upsets caused by disturbances in the system. It is, therefore, recommended that the PID control system developed should be applied on a physical set-up plant to study its real effect.

Ethanol-to-hydrocarbons reaction over HZSM-5: Enhanced ethanol/ethylene into C3+ hydrocarbons conversion by pristine external Brönsted acid sites

Here different Ethanol-To-Hydrocarbons (ETH) reaction pathways on the external surface and in the channels of HZSM-5 were revealed by comparing the catalytic performance of ZSM-5 samples with different distributions of acidic type and location: including (1) SiO2(Ⅱ)-NaZSM-5 with only internal Lewis (L) acidity, (2) NaZSM-5 with both internal and external L acidity, (3) SiO2(Ⅱ)-HZSM-5 with only internal Brönsted (B) & L acidity, and (4) HZSM-5 with B & L acidity on both external and internal surface. The primary product was the ethylene from ethanol dehydration over NaZSM-5, SiO2(Ⅱ)-NaZSM-5 and SiO2(Ⅱ)-HZSM-5, which exhibited the much low selectivities of C3+ hydrocarbons. However, except C2 aliphatics, plenty of C3+ aliphatics and aromatics were generated over the HZSM-5 which showed a higher ethanol conversion. These results indicate the B acid sites on external surface are responsible for a high-efficiency conversion of ethanol/ethylene into C3+ hydrocarbons via double-cycle process, which cannot likely occur on the acidic internal-surface in micropores due to both the much low dimerization reactivity of ethylene and the severe space-restriction effect there. Both internal and external L acid sites are only involved in the catalytic ethanol dehydration, which is also catalyzed by internal and external B acidity. These reaction pathways on the external surface of HZSM-5 were further confirmed by the ETH reaction results over two mesoporous materials (i.e., γ-Al2O3 with only L acidity and B2O3-γ-Al2O3 with both L and B acidity).

Ethylene production via ethanol dehydration over desilicated ZSM-5 catalyst

The catalytic dehydration of ethanol is a potential alternative route to synthesize ethylene apart from the traditional method which depends on fossil fuels. This report successfully prepared modified ZSM-5 with mesopores using desilication methods to enhance ethanol catalytic dehydration performance and ethylene production at lower temperature. The modified zeolite have the external surface area increased by 3.5 times and a higher dehydration efficiency compared with the original sample especially at temperatures below 220°C. Increasing reaction temperatures and gas houly space velocity (GHSV) increased the dehydration efficiency while increasing the inlet ethanol concentration had opposite effect. Significantly, the ethanol conversion over modified zeolite remained above 90 % when the GHSV increased to 36000 h‑1 after the time-on-stream of 24 h.

Development of a New Ternary Al2O3-HAP-Pd Catalyst for Diethyl Ether and Ethylene Production Using the Preferential Dehydration of Ethanol.

This study aims to convert ethanol to higher value-added products, particularly diethyl ether and ethylene using the catalytic dehydration of ethanol. Hence, the gas-phase dehydration of ethanol over Al2O3-HAP catalysts as such and modified by addition of palladium (Pd) in a microreactor was evaluated. The commercial Al2O3–HAP catalyst was first prepared by the physical mixing method, and then, the optimal ratio of the Al2O3–HAP catalyst (2:8 by wt %) was impregnated with Pd to develop a new functional catalyst to alter surface acidity. Based on the results, the combination of Al2O3 and HAP catalysts generated significant quantities of weak acid sites which demonstrates an enhancement in catalytic activity. In addition, Pd modification in the optimal composition ratio of the Al2O3–HAP catalyst extremely increased the amount of weak acid sites as well as weak acid density due to the synergistic effect between the Pd and Al2O3–HAP catalyst that are supposed to suggest the active sites in the reaction. Among all catalysts, the Al20-HAP80-Pd catalyst displayed brilliant catalytic performance in the course of diethyl ether yield (ca. 51.0%) at a reaction temperature of 350 °C and ethylene yield (ca. 75.0%) at a reaction temperature of 400 °C having an outstanding stability under time-on-stream for 10 h. This is recognized to the combination of the effects of weak acid sites (Lewis acidity), small amount of strong acid sites, and structural characteristics of the catalytic materials used.

Sonochemically prepared hierarchical MFI-type zeolites as active catalysts for catalytic ethanol dehydration

In this paper, the ultrasonic-assisted desilication technique was reported as an attractive and efficient way for the preparation of hierarchical zeolites with MFI structure type. The prepared materials were used as active catalysts for the dehydration of ethanol into diethyl ether and ethylene. For all catalysts, the selectivity to diethyl ether was ca 95% or higher up to 210 °C, with catalytic activity in the range of 40–68%. In case of desilicated zeolites, at 270–290 °C, the conversion of ethanol was full with selectivity to ethylene ca 80%. MFI-type commercial zeolite was treated with a sodium and/or tetrabutylammonium hydroxide aqueous solutions (NaOH or NaOH/TBAOH) for 30 min. In the case of the application of ultrasounds, a QSonica Q700 sonicator (60 W and 20 kHz) equipped with a “1” diameter horn was used. In all cases, desilication was performed in an ice bath in order to keep the procedure conditions at low temperature.It was indicated that the use of ultrasounds during desilication procedure caused higher extraction of silicon and aluminum, which was connected with an elevated mesoporosity in relation to the samples modified in the absence of ultrasounds. Ultrasonic-assisted treatment of MFI-type zeolite caused also an apparent formation of numerous holes inside zeolite grains, resembling the look of “swiss cheese”. Furthermore, it was indicated that the samples prepared using ultrasonic irradiation exhibited enhanced catalytic properties in the dehydration of ethanol. For instance, MFI-type zeolite treated with NaOH/TBAOH alkaline mixture containing 10 mol% of TBAOH in the presence of ultrasounds (M−10 s) demonstrated higher both conversion of ethanol (59% vs. 47%) and selectivity to diethyl ether (95% vs. 93%) in comparison with zeolite modified conventionally (M−10c).The best catalyst was zeolite ultrasonically desilicated with NaOH/TBAOH solution of 70 mol% of TBAOH (M-70s). Generally, this catalyst indicated the highest conversion of ethanol, very high selectivity to diethyl ether (94-100%) at 150-210 °C and the highest selectivity to ethylene among investigated catalysts (21%, 66% and 84%) at 230 °C, 250 oC and 270 °C.

Ethanol-ethylene conversion mechanism on hydrogen boride sheets probed by in situ infrared absorption spectroscopy.

Two-dimensional hydrogen boride (HB) sheets were recently demonstrated to act as a solid acid catalyst in their hydrogen-deficient state. However, both the active sites and the mechanism of the catalytic process require further elucidation. In this study, we analyzed the conversion of ethanol adsorbed on HB sheets under vacuum during heating using in situ Fourier transform infrared (FT-IR) absorption spectroscopy with isotope labelling. Up to 450 K, the FT-IR peak associated with the OH group of the adsorbed ethanol molecule disappeared from the spectrum, which was attributed to a dehydration reaction with a hydrogen atom from the HB sheet, resulting in the formation of an ethyl species. At temperatures above 440 K, the number of BD bonds markedly increased in CD3CH2OH, compared to CH3CD2OH; the temperature dependence of the formation rate of BD bonds was similar to that of the dehydration reaction rate of ethanol on HB sheets under steady-state conditions. The rate-determining step of the dehydration of ethanol on HB was thus ascribed to the dehydrogenation of the methyl group of the ethyl species on the HB sheets, followed by the immediate desorption of ethylene. These results show that the catalytic ethanol dehydration process on HB involves the hydrogen atoms of the HB sheets. The obtained mechanistic insights are expected to promote the practical application of HB sheets as catalysts.

Elucidation of Pd modification effect on catalytic behaviors of γ-Al2O3-P catalysts toward ethanol dehydration and dehydrogenation

The catalytic ethanol dehydration and dehydrogenation over γ-Al2O3-P catalysts with Pd modification were investigated. The Al2O3-P is promising to obtain the highest yield of diethyl ether (ca. 38.4%) at 350 °C attributing to increased portion of weak/moderate to strong acid site. Further investigation was conducted with Pd modification on this catalyst. It revealed that the 0.5Pd/Al2O3-P catalyst produced diethyl ether yield of ca. 33.3% at 350 °C with significant amount of acetaldehyde at low temperature. Increased reaction temperature to 400 °C obtained the highest ethylene yield (ca. 43.7%) with this catalyst because of both acid site and Pd site.

Kinetic and mechanistic study of ethanol dehydration to diethyl ether over Ni-ZSM-5 in a closed batch reactor

In the present work, mechanistic pathways and kinetics of catalytic dehydration of ethanol were investigated in a closed batch reactor for the formation of diethyl ether, and ethylene over the synthesized NiO loaded HZSM-5 in the range of 160–240 °C. The effect of the presence of water on reaction performance was also evaluated. No significant negative impact of water over diethyl ether yield was observed up to 1:1 ethanol–water molar ratio. The proposed two-step kinetic model highlights the mechanistically essential comparison between the strong (Bronsted) and weak (Lewis) acid sites of catalyst for ethanol conversion to diethyl ether. Intramolecular dehydration of ethanol over strong acid sites led to ethylene formation. Enhancement of weak acid sites due to NiO loading over HZSM-5 led to interestingly higher yields of diethyl ether by a combination of ethylene and ethanol. Optimal consideration for maximum conversions was observed with high reusability. Graphical abstract for ethanol dehydration on Ni-HZSM-5 catalyst.

Synthesis of Highly Selective and Stable Co-Cr/SAPO-34 Catalyst for the Catalytic Dehydration of Ethanol to Ethylene

In this study, silicoaluminophosphate (SAPO)-34 and Me (Me = Cr, Co)-modified SAPO-34 were synthesized and used as catalysts to investigate the catalytic performance by means of a probe reaction from ethanol to ethylene. The metal oxides were loaded on the SAPO-34 support via an impregnation method. The synthesized catalysts were characterized using XRD, SEM, EDX, FT-IR, NH3-TPD, BET, and TGA techniques. Compared to SAPO-34, SAPO-34 doped with metal oxides showed the same chabazite (CHA) topology. The structure and properties of the catalyst were further optimized by varying the amount of Me. The experimental results showed that Co-Cr/SAPO-34 exhibited the best catalytic performance when the reaction temperature reached 400 °C at a weight hourly space velocity (WHSV) of 3.5 h−1, for which the single-pass conversion of ethanol was determined as 99.15%, and the selectivity of ethylene was 99.4% at an optimum catalytic performance in the reaction of up to 600 min. In addition, Co-Cr/SAPO-34 exhibited better catalytic activity and anti-coking ability than pure SAPO-34, which was attributed to its enhanced pore structure and moderate acidity. It can also be concluded from the results of this experiment that the performance of the Co-Cr bimetal-supported catalyst is better than that of the Cr mono-metal catalyst.

Temperature and ethanol concentration effects on catalytic ethanol dehydration behaviors over alumina-spherical silica particle composite catalysts

The catalytic dehydration of ethanol was studied over spherical silica particle (SSP) and alumina-silica composite (Al-SSP). The catalysts were prepared by the modified sol-gel method with various alumina content ranging from 20 to 80 mol%. The 60Al-SSP catalyst exhibited the highest weak (Lewis) and total acid site giving the best ethanol conversion of 98% and ethylene selectivity of 99% at 400 °C and enhanced the catalytic performance with the excellent activity and stability with TOS for 10 h. Changing acid sites of catalyst due to water effect in different ethanol concentrations also led to a better ethylene selectivity.

MoZn /AlPO4-5 zeolite: Preparation, structural characterization and catalytic dehydration of ethanol

Aluminophosphate compounds (AlPO4-5) with the AFI structure framework are important members of microporous zeolites group and molecular sieves materials because having an enormous variety of structures leading to high potential catalytic applications. AlPO4-5 molecular sieves have been prepared via the hydrothermal reaction by using triethylamine as a template. Molybdenum and zinc bimetal supported AlPO4-5 zeolite catalysts (MoZn/AlPO4-5) were prepared using a co-impregnation method with different molar ratios. The obtained samples were described by the physicochemical characterizations techniques. The bimetal ratios effect towards the dehydration of ethanol was investigated. MoZn(4)/AlPO4-5 exhibit the most active catalyst towards ethylene formation and the parent AlPO4-5 was the least active but with high selectivity towards diethyl ether production. This conversion convinced by ZnMoO4 phase formation during Mo and Zn oxides interactions leading to improving the acid sites which are a favorite environment and augment to ethylene formation.

Catalytic Dehydration of Ethanol over W/TiO2 Catalysts Having Different Phases of Titania Support

This study aims to investigate the catalytic behaviors on W/TiO2 catalysts having different phases of TiO2 towards catalytic dehydration of ethanol to higher value products including ethylene, diethyl ether, and acetaldehyde. In fact, TiO2 support with different crystalline phases can result in differences of physico-chemical properties of the catalyst. Therefore, the present work reports on the catalytic behaviors that were altered with different phases of TiO2 in catalytic ethanol dehydration to diethyl ether or ethylene as a major product. To prepare the catalysts, three different phases [anatase (A), rutile (R), and mixed phases (P25)] of TiO2 supports were impregnated with 10 wt% of tungsten (W). It was found that the W/TiO2-P25 catalyst revealed higher activity among other catalysts. At 300 °C, all catalysts can produce the diethyl ether yield of 24.1%, 22.8%, and 10.6% for W/TiO2-P25, W/TiO2-A, and W/TiO2-R catalysts, respectively. However, when the reaction temperature was increased to 400°C, ethylene is the major product. The W/TiO2-P25 and W/TiO2-A catalysts render the ethylene yield of 60.3% and 46.2%, respectively, whereas only 15.9% is obtained from W/TiO2-R catalyst. The most important parameter influencing their catalytic properties appears to be the proper pore structure, acidity, and distribution of W species. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Tuning of catalytic behaviors in ethanol dehydration with oxygen cofeeding over Pd-HBZ catalyst for ethylene production at low temperature

The catalytic ethanol dehydration with oxygen cofeeding over different pretreated Pd-HBZ catalysts was investigated. The catalyst was pretreated with different gas including air, nitrogen, and hydrogen. It was tested in ethanol dehydration in the presence and absence of oxygen cofeeding. It was significantly found that with the presence of oxygen cofeeding, the complete ethanol conversion was obtained at very low temperature (ca. 200 °C) and ethylene was a major product. This can be attributed to increased moderate and strong acid sites of catalyst by oxygen cofeeding. In addition, the different gas pretreatment seemed to have less effect on catalytic behaviors.

Pd Modification and Supporting Effects on Catalytic Dehydration of Ethanol to Ethylene and Diethyl Ether over W/TiO2 Catalysts.

In the present work, the palladium (Pd) modification and supporting effect of W/TiO2 catalysts on catalytic ethanol dehydration to ethylene and diethyl ether were investigated. The Pd modification with different sequence of Pd and W impregnation on the catalysts was prepared by the incipient wetness impregnation technique. The catalyst characterization and activity testing revealed that the different sequence during impregnation influenced the physicochemical properties and ethanol conversion of catalyst. The differences in structure and surface properties were investigated by XRD, BET, SEM, EDX, XPS and NH3-TPD. Upon the reaction temperature between 200 to 400°C, it was found that the conversion increased with increasing of temperature for all catalysts. The Pd incorporated into catalysts enhanced the ethanol conversion depending on the sequence of impregnation. At low temperature (ca. 200 to 300°C), diethyl ether is a major product and the Pd modification over W/TiO2 catalyst resulted in increased diethyl ether yield. This is because an increase of ethanol conversion was obtained with Pd modification, while diethyl ether selectivity did not change. This can be attributed to the higher amount of weak acids sites present after Pd modification into catalyst. Among all catalysts, the PdW/TiO2 catalyst (coimpregnation) achieved the highest diethyl ether yield of 41.4% at 300℃. At high temperature (ca. 350 to 400°C), ethylene is the major product. The W/Pd/TiO2 catalyst (with sequential impregnation of Pd on TiO2 followed by W) exhibited the highest ethylene yield of 68.1% at 400°C. It can be concluded that the modification of Pd onto W/TiO2 upon different sequence of Pd and W impregnation can improve the diethyl ether and ethylene yield in catalytic ethanol dehydration.

Catalytic Dehydration of Ethanol over WOx Nanoparticles Supported on MFI (Mobile Five) Zeolite Nanosheets

Ethylene can be synthesized in a renewable manner by dehydrating bioethanol over supported metal oxide nanoparticle catalysts. Here, a series of nanoparticulate tungsten oxides supported on MFI (Mobil five) zeolite nanosheets was prepared at different W loadings (1 to 6 mol %) using the incipient wetness method and investigated with respect to the ability to catalyze the dehydration of ethanol. The resulting samples were characterized by X-ray diffraction, electron microscopy, N2 isotherms, X-ray absorption fine structures, and by the temperature-programmed desorption of NH3. The results obtained showed that WOx nanoparticles were homogeneously distributed over the entire void space of nanosheet samples up to a loading of 2 mol %, after which large WOx nanoparticles with needle-like morphology were formed on the surface of the zeolite nanosheet beyond 2mol%. The number of acid sites increased with WOx loading and, as a result, EtOH conversion progressively increased with WOx loading up to 6 mol %. At reaction temperatures of >390 °C, homogeneously distributed WOx nanoparticles showed slightly higher ethylene selectivity than nano-needle structured WOx. However, nano-needle structured WOx exhibited greater catalytic stability. In terms of ethylene yield over 8 h, needle-like WOx nanoparticles were found to be more suitable for the acid-catalyzed dehydration of ethanol than small-sized WOx nanoparticles.

Influence of Phosphoric Acid Modification on Catalytic Properties of γ-χ Al2O3 Catalysts for Dehydration of Ethanol to Diethyl Ether

In this present work, diethyl ether, which is currently served as promising alternative fuel for diesel engines, was produced via catalytic dehydration of ethanol over H3PO4-modified g-c Al2O3 catalysts. The impact of H3PO4 addition on catalytic performance and characteristics of catalysts was investigated. While catalytic dehydration of ethanol was performed in a fixed-bed microreactor at the temperature ranging from 200ºC to 400ºC under atmospheric pressure, catalyst characterization was conducted by inductively coupled plasma (ICP), X-ray diffraction (XRD), N2 physisorption, temperature-programmed desorption of ammonia (NH3-TPD) and thermogravimetric (TG) analysis. The results showed that although the H3PO4 addition tended to decrease surface area of catalyst resulting in the reduction of ethanol conversion, the Al2O3 containing 5 wt% of phosphorus (5P/Al2O3) was the most suitable catalyst for the catalytic dehydration of ethanol to diethyl ether since it exhibited the highest catalytic ability regarding diethyl ether yield and the quantity of coke formation as well as it had similar long-term stability to conventional Al2O3 catalyst. The NH3-TPD profiles of catalysts revealed that catalysts containing more weak acidity sites were preferred for dehydration of ethanol into diethyl ether and the adequate promotion of H3PO4 would lower the amount of medium surface acidity with increasing catalyst weak surface acidity. Nevertheless, when the excessive amount of H3PO4 was introduced, it caused the destruction of catalysts structure, which resulted in the catalyst incapability due to the decrease in active surface area and pore enlargement.