Effects of Process Factors on Carbon Dioxide Reforming of Methane over Ni/SBA-15 Catalyst

The process of CO2 reformation of CH4 was conducted over a 5% Ni/SBA-15 catalyst under various experimental conditions. Operating temperature (600-750 �C), gas hourly space velocity (4000-12000 hr-1), and CO2/CH4 feed molar ratio (0.67-1.50) were selected as independent parameters (factors). Process performances were evaluated as conversions of CH4 (21.1-79.6%) and CO2 (42.4-98.7%) as well as H2/CO product molar ratio (0.573-0.992). All process performances were enhanced at higher levels of temperature and low values of gas velocity. An increase in feed molar ratio has determined a significant increase in CH4 conversion and a slighter decrease in CO2 conversion and H2/CO molar ratio. A statistical model based on a 23 factorial plan was used to predict the process performances depending on its factors.

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Experimental Study on CO2 Methanation over Ni/Al2O3, Ru/Al2O3, and Ru-Ni/Al2O3 Catalysts

Catalysts ◽

10.3390/catal10101112 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1112 ◽

Cited By ~ 2

Author(s):

Rei-Yu Chein ◽

Chih-Chang Wang

Keyword(s):

Space Velocity ◽

Molar Ratio ◽

Ni Catalyst ◽

Co2 Conversion ◽

Co2 Methanation ◽

Temperature Changes ◽

Good Thermal Stability ◽

Reverse Water Gas Shift ◽

Optimum Reaction ◽

Shift Reaction

CO2 methanation is recognized as one of the best technologies for storing intermittent renewable energy in the form of CH4. In this study, CO2 methanation performance is investigated using Ni/Al2O3, Ru/Al2O3, and Ru-Ni/Al2O3 as the catalysts under conditions of atmospheric pressure, a molar ratio of H2/CO2 = 5, and a space velocity of 5835 h−1. For reaction temperatures ranging from 250 to 550 °C, it was found that the optimum reaction temperature is 400 °C for all catalysts studied. At this temperature, the maximum values of CO2 conversion, H2 efficiency, and CH4 yield and lowest CO yield can be obtained. With temperatures higher than 400 °C, reverse CO2 methanation results in CO2 conversion and CH4 yield decreases with increased temperature, while CO is formed due to reverse water-gas shift reaction. The experimental results showed that CO2 methanation performance at low temperatures can be enhanced greatly using the bimetallic Ru-Ni catalyst compared with the monometallic Ru or Ni catalyst. Under ascending-descending temperature changes between 250 °C and 550 °C, good thermal stability is obtained from Ru-Ni/Al2O3 catalyst. About a 3% decrease in CO2 conversion is found after three continuous cycles (74 h) test.

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Characteristics and Properties of Absorption Materials for Mercury Removal at High Temperature

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.730.185 ◽

2017 ◽

Vol 730 ◽

pp. 185-189

Author(s):

Han Wen Cheng ◽

Ching Tsung Yu

Keyword(s):

Operating Temperature ◽

Space Velocity ◽

Mercury Removal ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Surface Areas ◽

Electron Detection ◽

Metal Ratio ◽

Structure Analyzer

In this study, some metal-M/aluminum carbonate absorption materials with molar ratio of M:Al=3:1 were manufactured. There was Cu–Al, Mn–Al, Fe–Al three kinds of sorbents synthesized by co-precipitate method. The physicochemical structures during mercury removal were analyzed by a surface area and pore structure analyzer (BET), an X-ray diffraction (XRD), a scanning electron microscope coupled with an electron detection scanning (SEM/EDS), and X-ray fluorescence (XRF). The results showed that surface areas for metal-M/aluminum carbonate sorbents were only about 11~12 m2/g and the metal ratio loaded was more than 80%. Lab-scale tests mercury removal efficiency in the temperature range of 200–300 oC indicated that there was an improvement in the performance of mercury removal by increasing reaction temperature. Cu–Al, Fe–Al and Mn–Al all three sorbents reached their absorption equivalent of 256.6, 253.3 and 247.0 μg/g under 300 oC operating temperature and 19736 h-1 gas hourly space velocity. Additionally, the presence of transition metals can significantly improve the efficiency of mercury removal of the absorption materials.

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CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Catalysts ◽

10.3390/catal10101201 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1201

Author(s):

Danbee Han ◽

Yunji Kim ◽

Hyunseung Byun ◽

Wonjun Cho ◽

Youngsoon Baek

Keyword(s):

Reaction Temperature ◽

Photoelectron Spectroscopy ◽

Conversion Rate ◽

Space Velocity ◽

Molar Ratio ◽

Co2 Conversion ◽

X Ray Diffraction ◽

Co2 Methanation ◽

X Ray ◽

Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

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Process Intensification of Methane Production via Catalytic Hydrogenation in the Presence of Ni-CeO2/Cr2O3 Using a Micro-Channel Reactor

Catalysts ◽

10.3390/catal11101224 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1224

Author(s):

Vut Tongnan ◽

Youssef Ait-lahcen ◽

Chuthamas Wongsartsai ◽

Chalempol Khajonvittayakul ◽

Nuchanart Siri-Nguan ◽

...

Keyword(s):

Activation Energy ◽

Process Intensification ◽

Catalytic Performance ◽

Molar Ratio ◽

Micro Channel ◽

Co2 Conversion ◽

Channel Reactor ◽

Mechanistic Pathway ◽

Slight Amount ◽

Feed Molar Ratio

A slight amount of Cr2O3 segregation in 40 wt% NiO/Ce0.5Cr0.5O2 was presented at the surface. The best catalytic performance towards the reaction was achieved at 74% of CO2 conversion and 100% CH4 selectivity at 310 °C, the reactant (H2/CO2) feed molar ratio was 4, and the WHSV was 56,500 mlN·h−1·g−1cat. The mechanistic pathway was proposed through carbonates and formates as a mediator during CO2 and H2 interaction. Activation energy was estimated at 4.85 kJ/mol, when the orders of the reaction were ranging from 0.33 to 1.07 for nth-order, and 0.40 to 0.53 for mth-order.

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Ex-LDH-Based Catalysts for CO2 Conversion to Methanol and Dimethyl Ether

Catalysts ◽

10.3390/catal11050615 ◽

2021 ◽

Vol 11 (5) ◽

pp. 615

Author(s):

Mauro Mureddu ◽

Sarah Lai ◽

Luciano Atzori ◽

Elisabetta Rombi ◽

Francesca Ferrara ◽

...

Keyword(s):

Dimethyl Ether ◽

Surface Acidity ◽

Molar Ratio ◽

Bifunctional Catalysts ◽

Co2 Conversion ◽

Experimental Conditions ◽

Hydrogenation Catalysts ◽

Methanol Production ◽

Bulk Chemicals ◽

Renewable Hydrogen

CO2-derived methanol and dimethyl ether can play a very important role as fuels, energy carriers, and bulk chemicals. Methanol production from CO2 and renewable hydrogen is considered to be one of the most promising pathways to alleviate global warming. In turn, methanol could be subsequently dehydrated into DME; alternatively, one-step CO2 conversion to DME can be obtained by hydrogenation on bifunctional catalysts. In this light, four oxide catalysts with the same Cu and Zn content (Cu/Zn molar ratio = 2) were synthesized by calcining the corresponding CuZnAl LDH systems modified with Zr and/or Ce. The fresh ex-LDH catalysts were characterized in terms of composition, texture, structure, surface acidity and basicity, and reducibility. Structural and acid–base properties were also studied on H2-treated samples, on which specific metal surface area and dispersion of metallic Cu were determined as well. After in situ H2 treatment, the ex-LDH systems were tested as catalysts for the hydrogenation of CO2 to methanol at 250 °C and 3.0 MPa. In the same experimental conditions, CO2 conversion into dimethyl ether was studied on bifunctional catalysts obtained by physically mixing the exLDH hydrogenation catalysts with acid ferrierite or ZSM-5 zeolites. For both processes, the effect of the Al/Zr/Ce ratio on the products distribution was investigated.

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Modelling of Jatropha Oil Hydrocracking in a Trickle-Bed Reactor to Produce Green Fuel

International Journal of Chemical Engineering ◽

10.1155/2021/7079459 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Yuswan Muharam ◽

Dianursanti ◽

Andrey Sapati Wirya

Keyword(s):

Heat Transfer ◽

Optimum Condition ◽

Molar Ratio ◽

Inlet Temperature ◽

Jatropha Oil ◽

Gas Velocity ◽

Trickle Bed Reactor ◽

Green Fuel ◽

Feed Molar Ratio ◽

Good Heat

Trickle-bed reactor (TBR) modelling to produce green fuel via hydrocracking of jatropha oil using silica-alumina-supported Ni-W catalysts was performed in this research. The objectives of this study are to obtain a TBR with good heat transfer and the optimum condition for high purities of products. A two-dimensional axisymmetric model with a diameter of 0.1 m and a length of 10 m was used as a representative of the actual TBR system. Heterogeneous phenomenological models were developed considering mass, energy, and momentum transfers. The optimisation was conducted to obtain the highest green fuel purity by varying catalyst particle diameter, inlet gas velocity, feed molar ratio, and inlet temperature. The simulation shows that a TBR with an aspect ratio of 100 has achieved a good heat transfer. The diesel purity reaches 44.22% at 420°C, kerosene purity reaches 21.39% at 500°C, and naphtha purity reaches 25.30% at 500°C. The optimum condition is reached at the catalyst diameter of 1 mm, the inlet gas velocity of 1 cm/s, the feed molar ratio of 105.5, and the inlet temperature at 500°C with the green fuel purity of 69.4%.

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CO2 Methanation of Biogas Over 20 wt% Ni-Mg-Al Catalyst: On the Effect of N2, CH4, and O2 on CO2 Conversion Rate

10.20944/preprints202008.0650.v1 ◽

2020 ◽

Author(s):

Danbee Han ◽

Yunji Kim ◽

Hyunseung Byun ◽

Wonjun Cho ◽

Youngsoon Baek

Keyword(s):

Reaction Temperature ◽

Photoelectron Spectroscopy ◽

Conversion Rate ◽

Space Velocity ◽

Bet Surface Area ◽

Molar Ratio ◽

Co2 Conversion ◽

Co2 Methanation ◽

X Ray ◽

Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000/h, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000/h), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The catalyst was stable for approximately 200 h at a GHSV of 30,000/h and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

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Catalysts for hydrogenation of CO2 into components of motor fuels

Catalysis and petrochemistry ◽

10.15407/kataliz2020.30.001 ◽

2020 ◽

pp. 1-18

Author(s):

Yu.V. Bilokopytov ◽

◽

S.L. Melnykova ◽

N.Yu. Khimach ◽

◽

...

Keyword(s):

Carbon Dioxide ◽

Heterogeneous Catalysts ◽

Fossil Fuels ◽

Catalyst Stability ◽

Co2 Conversion ◽

Active Components ◽

Synthesis Conditions ◽

Hydrogenation Of Co2 ◽

Mesoporous Zeolites ◽

Motor Fuels

CO2 is a harmful greenhouse gas, a product of chemical emissions, the combustion of fossil fuels and car exhausts, and it is a widely available source of carbon. The review considers various ways of hydrogenation of carbon dioxide into components of motor fuels - methanol, dimethyl ether, ethanol, hydrocarbons - in the presence of heterogeneous catalysts. At each route of conversion of CO2 (into oxygenates or hydrocarbons) the first stage is the formation of CO by the reverse water gas shift (rWGS) reaction, which must be taken into account when catalysts of process are choosing. The influence of chemical nature, specific surface area, particle size and interaction between catalyst components, as well as the method of its production on the CO2 conversion processes is analyzed. It is noted that the main active components of CO2 conversion into methanol are copper atoms and ions which interact with the oxide components of the catalyst. There is a positive effect of other metals oxides additives with strong basic centers on the surface on the activity of the traditional copper-zinc-aluminum oxide catalyst for the synthesis of methanol from the synthesis gas. The most active catalysts for the synthesis of DME from CO2 and H2 are bifunctional. These catalysts contain both a methanol synthesis catalyst and a dehydrating component, such as mesoporous zeolites with acid centers of weak and medium strength, evenly distributed on the surface. The synthesis of gasoline hydrocarbons (≥ C5) is carried out through the formation of CO or CH3OH and DME as intermediates on multifunctional catalysts, which also contain zeolites. Hydrogenation of CO2 into ethanol can be considered as an alternative to the synthesis of ethanol through the hydration of ethylene. High activation energy of carbon dioxide, harsh synthesis conditions as well as high selectivity for hydrocarbons, in particular methane remains the main problems. Further increase of selectivity and efficiency of carbon dioxide hydrogenation processes involves the use of nanocatalysts taking into account the mechanism of CO2 conversion reactions, development of methods for removing excess water as a by-product from the reaction zone and increasing catalyst stability over time.

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Dimethyldisulphide Hydrodesulphurization on NiCoMo / Al2O3 Catalyst

Revista de Chimie ◽

10.37358/rc.17.7.5703 ◽

2017 ◽

Vol 68 (7) ◽

pp. 1496-1500

Author(s):

Rami Doukeh ◽

Mihaela Bombos ◽

Ancuta Trifoi ◽

Minodora Pasare ◽

Ionut Banu ◽

...

Keyword(s):

Good Accuracy ◽

Fixed Bed ◽

Continuous System ◽

Space Velocity ◽

Molar Ratio ◽

Catalytic Reactor ◽

Liquid Hourly Space Velocity ◽

Hydrodesulfurization Process ◽

Al2o3 Catalyst ◽

Simplified Kinetic Model

Hydrodesulphurization of dimethyldisulphide was performed on Ni-Co-Mo /�-Al2O3 catalyst. The catalyst was characterized by determining the adsorption isotherms, the pore size distribution and the acid strength. Experiments were carried out on a laboratory echipament in continuous system using a fixed bed catalytic reactor at 50-100�C, pressure from 10 barr to 50 barr, the liquid hourly space velocity from 1h-1 to 4h-1 and the molar ratio H2 / dimethyldisulphide 60/1. A simplified kinetic model based on the Langmuir�Hinshelwood theory, for the dimethyldisulphide hydrodesulfurization process of dimethyldisulphide has been proposed. The results show the good accuracy of the model.

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Enzymatic Process for Cystoseira barbata Valorization: Ethanol Production and Additional By-Products

Processes ◽

10.3390/pr9050741 ◽

2021 ◽

Vol 9 (5) ◽

pp. 741

Author(s):

Doinita-Roxana Cioroiu Tirpan ◽

Ancaelena Eliza Sterpu ◽

Claudia Irina Koncsag ◽

Alina Georgiana Ciufu ◽

Tănase Dobre

Keyword(s):

Ethanol Production ◽

Alcoholic Fermentation ◽

Ethanol Yield ◽

Product Yield ◽

Liquid Ratio ◽

Experimental Conditions ◽

Factors Affecting ◽

Cystoseira Barbata ◽

Main Factors ◽

Process Factors

The aim of this study is to evaluate the potential of dried Cystoseira barbata alga for ethanol production through alcoholic fermentation. The influence of the main factors affecting the fermentation are studied in the frame of a 23 factorial experimental plan. The main factors influencing the process are the fermentation temperature (t from 25 °C to 35 °C), the solid to liquid ratio (S/L from 0.040 g/g to 0.080 g/g), and the cellulase ratio (R from 8 U/g d.m to 16 U/g d.m.). The maximum volatile compounds yield of 0.2808 g/g d.m and ethanol yield of 0.0158 g/g d.m were favored by the following experimental conditions: process temperature of 35 °C, solid to liquid ratio of 0.0415, and enzyme ratio of 16 U/g d.m. A statistical model was used to correlate the product yield with the process factors. Additionally, 19 interesting bioactive compounds were found in the enzymatic hydrolysis and alcoholic fermentation broths which seem likely to maintain natural defence mechanisms against diseases and physical disorders.

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