Novel bifunctional catalysts based on crystalline multi-oxide matrices containing iron ions for CO2 hydrogenation to liquid fuels and chemicals

2016 ◽  
Vol 188 ◽  
pp. 545-563 ◽  
Author(s):  
N. Utsis ◽  
R. Vidruk-Nehemya ◽  
M. V. Landau ◽  
M. Herskowitz
Keyword(s):  
Active Sites ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Liquid Fuels ◽  
Metallic Oxide ◽  
Fe Oxide ◽  
Carbide Phases ◽  
Rwgs Reaction ◽  
In Series ◽  
Water Inhibition

Seven solid mono-, bi- and tri-metallic oxide matrices where Fe(2+,3+) ions are distributed in different chemical/spatial environments were synthesized and characterized by XRD, N2-adsorption and EDAX methods. After basification with potassium, all matrices were activated by carburization or reduction–carburization under conditions selected based on the TPC/TPR spectra, tailoring the carburization extent of iron. The performances of the activated Fe-based catalysts with respect to CO2 conversion and C5+ selectivity were measured in a fixed-bed reactor under standard conditions in transient and continuous operation modes in units containing one or three reactors in series with water separations between the reactors. The catalysts were characterized by XRD, N2-adsorption, HRTEM-EELS and XPS before and after steady-state operation in the reactors. It was found that the rate of CO2 conversion is not limited by thermodynamic equilibrium but is strongly restricted by water inhibition and it depends on the nature of the Fe-oxide precursor. The ratio between the FTS and RWGS rates, which determines the C5+ hydrocarbons productivity, is strongly affected by the nature of the Fe-oxide matrix. The catalysts derived from the Fe–Al–O spinel and Fe–Ba–hexaaluminate precursors displayed the best balance of the two functions RFTS/RRWGS = 0.77–0.78. They were followed by magnetite, CuFe–delafossite, K–ferrite, Fe–La–hexaaluminate and LaFe–perovskite with a gradual lowering of RFTS/RRWGS from 0.60 to 0.15 and a gradual decrease in the C5+ productivity. The active sites that enhance the RWGS reaction are located on the surface of the Fe-oxide phases, while the FTS and methanation reactions occur on the surface of the Fe-carbide phases.

On efficiency of vanadium-oxide promoter in cobalt Fischer – Tropsch catalysts

2021 ◽  
Vol 1 (1-2) ◽  
pp. 15
Author(s):  
Elham Yaghoobpour ◽  
Yahya Zamani ◽  
Saeed Zarrinpashne ◽  
Akbar Zamaniyan
Keyword(s):  
Vanadium Oxide ◽  
Active Sites ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bet Surface Area ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Fischer Tropsch ◽  
Co Conversion ◽  
Loading Amount

Promoters and their loading amount have crucial roles in cobalt Fischer – Tropsch catalysts. In this regard, the effects of vanadium oxide (V2O5) as a proposed promoter for Co catalyst supported on TiO2 have been investigated. Three catalysts with 0, 1, and 3 wt.% of V2O5 promoter loading are prepared by the incipient wetness impregnation method, and characterized by the BET surface area analyzer, XRD, H2-TPR, and TEM techniques. The fixed-bed reactor was employed for their evaluations. It was found that the catalyst containing 1 wt.% V2O5 has the best performance among the evaluated catalysts, demonstrating remarkable selectivity: 92 % C5+ and 5.7 % CH4, together with preserving the amount of CO conversion compared to the unpromoted catalyst. Furthermore, it is reported that the excess addition of V2O5 promoter (> 1 wt.%) in the introduced catalyst leads to the detrimental effect on the CO conversion and C5+ selectivity, mainly owing to diminished active sites by V2O5 loading.

Modified Cuo/ZnO/Al2O3 Catalysts for Methanol Synthesis from Co and CO2 Co-Hydrogenation

2013 ◽  
Vol 690-693 ◽  
pp. 1529-1534
Author(s):  
Wen Gui Gao ◽  
Hua Wang ◽  
Wen Yan Liu ◽  
Feng Jie Zhang
Keyword(s):  
Methanol Synthesis ◽  
Active Sites ◽  
Co Hydrogenation ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Total Carbon ◽  
X Ray Diffraction ◽  
Wet Impregnation ◽  
Temperature Programmed ◽  
Co Precipitation

A series of CuO-ZnO-Al2O3catalysts modified by different promoter were prepared by co-precipitation or incipient wet impregnation and characterized by X-ray diffraction (XRD), N2physisorption, hydrogen temperature-programmed reduction (H2-TPR) and carbon dioxide temperature-programmed desorption (CO2-TPD). The modified catalysts were tested for methanol synthesis from CO/CO2co-hydrogenation in a fixed bed reactor with feed containing CO, CO2and H2(CO:CO2:H2=1.0:1.08:6.24, volume radio). It is revealed that the catalysts modified by Zr, Mg, Ca has higher activity of methanol synthesis by CO and CO2co-hydrogenation. Especially, the addition of Zr enhances the conversion of total carbon and the selectivity of methanol, which is due to the improved surface area, much more active sites, and the synergistically interaction between CuO and ZnO caused by the addition of Zr promoter.

Methanol to Gasoline Conversion over CuO/ZSM-5 Catalyst Synthesized Using Sonochemistry Method

2018 ◽  
Vol 17 (2) ◽  
Author(s):  
Ehsan Kianfar ◽  
Mahmoud Salimi ◽  
Saeed Hajimirzaee ◽  
Behnam Koohestani
Keyword(s):  
Copper Oxide ◽  
Lewis Acid ◽  
Active Sites ◽  
Fixed Bed ◽  
Acid Sites ◽  
High Specific Surface Area ◽  
Fixed Bed Reactor ◽  
Lewis Acid Sites ◽  
Hydrocarbon Production ◽  
Methanol To Gasoline

Abstract In this research, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over CuO (5 %)/ZSM-5 and CuO (7 %)/ZSM-5 catalysts prepared via sonochemistry methods. Conversion of methanol to gasoline (MTG) has been carried out in a fixed bed reactor under atmospheric pressure and 400˚C temperature, over copper oxide on the synthesized ZSM-5 catalyst. The samples were characterized by XRD, SEM, TEM, BET, and FTIR techniques; in which good crystallinity and high specific surface area of synthesized zeolite were proved after impregnation of zeolite with copper. The present investigation suggests that the CuO/ZSM-5 catalyst made by sonochemistry method can increase the yield toward hydrocarbon production. It was concluded that impregnation of zeolite with copper oxide can alter the Brønsted/Lewis acid sites ratio and provide new Lewis acid sites over the surface of the ZSM-5. The main products of methanol to gasoline reaction over the catalyst that prepared via sonochemistry method were toluene, xylene, ethylbenzene, ethyl toluene, tetra methylbenzene, diethyl benzene and butylbenzene. The total amount of aromatics in the products was 80 % by using this catalyst. Our results suggest that catalyst synthesized by using sonochemistry shows better production yield toward hydrocarbons by affecting the distribution of active sites on the surface of the ZSM-5.

PdIn Catalysts in a Continuous Fixed Bed Reactor for the Nitrate Removal from Groundwater

2019 ◽  
Vol 17 (6) ◽  
Author(s):  
F. A. Marchesini ◽  
G. Mendow ◽  
N. P. Picard ◽  
F. M. Zoppas ◽  
V. S. Aghemo ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Catalytic Reduction ◽  
Bubble Column ◽  
Catalyst Activity ◽  
Nitrate Removal ◽  
Fixed Bed ◽  
High Water ◽  
Fixed Bed Reactor ◽  
Water Volume

Abstract The ground water (GW) is a real sample of water which contains nitrates (81 mg/L), carbonates and sulphates. This sample was treated by catalytic reduction in a bubble column fixed-bed reactor. The reaction conditions were room temperature and atmospheric pressure, and hydrogen was used as reducing agent. A comparison between the catalytic activity of Pd,In/SiO2 and Pd,In/Al2O3 catalysts was performed, giving the latter the best results regarding the nitrate conversion and the former the selectivity to nitrogen. Synthetic water containing nitrates (SW) and the groundwater (GW) with high salinity (81 mg/L nitrates) and humic acid content were treated in these conditions using HCl and CO2 as acidifiers. When the SW was acidified with CO2 at an H2 flow (2.17 mL/min), more than 50 % of conversion was obtained with an ammonia and nitrite concentrations of 0.44 and 0.92 ppm respectively. These results reached the level established by the WHO and the USEPA. However, both Pd,In/SiO2 and Pd,In/Al2O3 catalysts showed evidence of some deactivation process. This deactivation was higher in the GW sample, possibly due to the presence of Ca+2 and Mg+2 cations that precipitate on the active sites, and/or the presence of humic acids. The characterization studies indicated that, after the reaction, the composition of the metal phases was modified, specifically on their surface. As the catalyst activity is related to surface ratio Pd/In, a relative increase in the concentration of Pd decreases the activity and causes changes in the selectivity to N2. Some sintering of the metal particles was also observed to contribute to catalyst deactivation. Nevertheless, promising results were obtained since a high water volume could be treated with a relatively low amount of low metal loading catalysts.

scholarly journals Effect of hydraulic retention time on hydrodynamic behavior of anaerobic-aerobic fixed bed reactor treating cattle slaughterhouse effluent

2017 ◽  
Vol 39 (4) ◽  
pp. 469 ◽  
Author(s):  
Daiane Cristina de Freitas ◽  
Fernando Hermes Passig ◽  
Cristiane Kreutz ◽  
Karina Querne de Carvalho ◽  
Eudes José Arantes ◽  
...  
Keyword(s):  
Flow Regime ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Fixed Bed ◽  
Theoretical Models ◽  
Fixed Bed Reactor ◽  
Bromophenol Blue ◽  
Eosin Y ◽  
Hydrodynamic Behavior ◽  
In Series

The study of the hydrodynamic behavior in reactors provides characteristics of the flow regime and its anomalies that can reduce biological processes efficiency due to the decrease of the useful volume and the hydraulic retention time required for the performance of microbial activity. In this study, the hydrodynamic behavior of an anaerobic-aerobic fixed bed reactor, operated with HRT (hydraulic retention time) of 24, 18 and 12 hours, was evaluated in the treatment of raw cattle slaughterhouse wastewater. Polyurethane foam and expanded clay were used as support media for biomass immobilization. Experimental data of pulse type stimulus-response assays were performed with eosin Y and bromophenol blue, and adjusted to the single-parameter theoretical models of dispersion and N-continuous stirred tank reactors in series (N-CSTR). N-CSTR model presented the best adjustment for the HRT and tracers evaluated. RDT (residence time distribution) curves obtained with N-CSTR model in the assays with bromophenol blue resulted in better adjustment compared to the eosin Y. The predominant flow regime in AAFBR (anaerobic aerobic fixed bed reactor) is the N-CSTR in series, as well as the existence of preferential paths and hydraulic short-circuiting. 

Revisiting the Problem of Active Sites for Methane Combustion on Pd/Al2O3 by Operando XANES in a Lab-Scale Fixed-Bed Reactor

2010 ◽  
Vol 114 (20) ◽  
pp. 9439-9443 ◽  
Author(s):  
Santhosh Kumar Matam ◽  
M. H. Aguirre ◽  
A. Weidenkaff ◽  
D. Ferri
Keyword(s):  
Active Sites ◽  
Fixed Bed ◽  
Methane Combustion ◽  
Fixed Bed Reactor

scholarly journals Thermodynamic Insight in Design of Methanation Reactor with Water Removal Considering Nexus between CO2 Conversion and Irreversibilities

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7861
Author(s):  
Sayed Ebrahim Hashemi ◽  
Kristian M. Lien ◽  
Magne Hillestad ◽  
Sondre K. Schnell ◽  
Bjørn Austbø
Keyword(s):  
Energy Use ◽  
Homogeneous Model ◽  
Fixed Bed ◽  
Energy Systems ◽  
Fixed Bed Reactor ◽  
Water Removal ◽  
Intermediate Water ◽  
Co2 Conversion ◽  
Co2 Methanation ◽  
In Series

The inevitable nexus between energy use and CO2 emission necessitates the development of sustainable energy systems. The conversion of CO2 to CH4 using green H2 in power-to-gas applications in such energy systems has attracted much interest. In this context, the present study provides a thermodynamic insight into the effect of water removal on CO2 conversion and irreversibility within a CO2 methanation reactor. A fixed-bed reactor with one intermediate water removal point, representing two reactors in series, was modeled by a one-dimensional pseudo-homogeneous model. Pure CO2 or a mixture of CO2 and methane, representing a typical biogas mixture, were used as feed. For short reactors, both the maximum conversion and the largest irreversibilities were observed when the water removal point was located in the middle of the reactor. However, as the length of the reactor increased, the water removal point with the highest conversion was shifted towards the end of the reactor, accompanied by a smaller thermodynamic penalty. The largest irreversibilities in long reactors were obtained when water removal took place closer to the inlet of the reactor. The study discusses the potential benefit of partial water removal and reactant feeding for energy-efficient reactor design.

Review of Reactor and Catalyst in the Pyrolysis of Biomass for Liquid Fuels

2012 ◽  
Vol 512-515 ◽  
pp. 552-557
Author(s):  
Xiao Xiong Zhang ◽  
Guan Yi Chen ◽  
Yi Wang
Keyword(s):  
Alternative Fuels ◽  
Catalytic Pyrolysis ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Liquid Fuels ◽  
Thermochemical Conversion ◽  
Renewable Energy Resources ◽  
Bio Oil ◽  
Pyrolysis Of Biomass

Due to the rapid growth of energy consumption, fossil-based fuel is at the verge of extinction. Hence, the world needs new energy to substitute for the non-renewable energy resources. Various biomass resources have been discussed by virtue of the ability of generating alternative fuels, chemicals and energy-related products. To date, the utilization of biomass is mainly thermochemical conversion which involves combustion, gasification and pyrolysis. The focus, currently, is on the catalytic pyrolysis of biomass. A variety of reactors are designed and many new catalysts for the yields of liquid products and upgrading of bio-oil are investigated. Different reactors have their own unique characteristics, and fixed bed reactor is not complicated and can be controlled easily but is difficult to upsize. Fluidized bed has a good suitability for different kinds of biomass but is more complex in structure and more difficult to control. Compared with non-catalytic pyrolysis, the quality of bio-oil improves considerably in the presence of a catalyst. Different catalysts exert different effects on the upgrading of bio-oil. HZSM-5 can reduce a vast output of acid compounds and increases hydrocarbon yields. Au/Al2O3 catalyst leads to an increase of H2 yield. All the catalysts can promote the upgrading of pyrolysis products. Optimal yields and the best quality of bio-oil can be obtained by an appropriate reactor with a proper catalyst.

scholarly journals Optimal Fixed Bed Reactor Network Configuration for the Efficient Recycling of CO2 into Methanol

2021 ◽  
Author(s):  
Ali Elkamel ◽  
Gholam Reza Zahedi ◽  
Chris Marton ◽  
Ali Lohi
Keyword(s):  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Industrial Plant ◽  
Production Network ◽  
Heterogeneous Model ◽  
Methanol Production ◽  
In Series ◽  
Maximum Production Rate ◽  
Production Period ◽  
Reactor Network

An optimal design strategy of a network of fixed bed reactors for Methanol Production (MP) is proposed in this study. Both methanol production and profit spanning a production period of eight years have been set as objective functions to find the optimal production network. The conservation of mass and energy laws on a heterogeneous model of a single industrial methanol reactor was first developed. The model was solved numerically and was validated with industrial plant data. Different reactor network arrangements were then simulated in order to find an optimal superstructure. It was found that a structure of four reactors (two in series in parallel with another two in series) provide maximum production rate. The application of the more realistic objective function of profit showed that a configuration of two parallel reactors is the best configuration. This optimal structure produces 92 tons/day more methanol than a single reactor.

Thermal Decomposition of Methane for Production of COx Free Hydrogen over Ni-Supported Y Zeolite Based Catalysts

2014 ◽  
Vol 679 ◽  
pp. 194-199
Author(s):  
Md. Nasir Uddin ◽  
W.M.A. Wan Daud ◽  
Hazzim F. Abbas
Keyword(s):  
Reaction Time ◽  
Hydrogen Production ◽  
Active Sites ◽  
Formation Rate ◽  
Fixed Bed ◽  
Catalytic Decomposition ◽  
Carbon Accumulation ◽  
Fixed Bed Reactor ◽  
Y Zeolite ◽  
Filamentous Carbon

The thermo-catalytic decomposition (TCD) of methane has attracted the attention of numerous researchers’ around the world as an ideal approach for hydrogen production, which in turns, can be used as an appropriate feeding gas in fuel cells operating at low temperatures. The TCD of methane is capable to produce a valuable by–product, pure carbon, which can excessively alleviate the total cost of the process. In this study, we report TCD of methane over 30% Ni supported Y zeolite catalyst at 550 and 600 °C was conducted in a fixed bed reactor and the yield of hydrogen from the reactor was analyzed by GC. As can be observed that, the TCD of methane over Ni-supported Y zeolite showed maximum conversion (31 and 15.90 % at 600 and 550 °C, respectively) at the initial stages and on stream of reaction time, it decreased gradually; and ultimately, deactivated the catalyst completely. The cause for this is the formation of encapsulating carbon on Ni active sites which deactivates the catalyst over the course of reaction time. Hydrogen production rate, carbon accumulation (CA) and carbon formation rate (CFR) were investigated at three representative times for both temperatures. The CFR analysis showed that the growth of filamentous carbon was steady-state at the first stage and then reduced to a relic activity and it remains constant during the rest of the reaction. The descriptive dissemination of methane TCD over Ni-supported Y zeolite has been speculated in this paper.

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