scholarly journals Bioalcohol Reforming: An Overview of the Recent Advances for the Enhancement of Catalyst Stability

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 665 ◽  
Author(s):  
Vincenzo Palma ◽  
Concetta Ruocco ◽  
Marta Cortese ◽  
Marco Martino
Keyword(s):  
Fossil Fuels ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Catalyst Stability ◽  
Side Reactions ◽  
Catalytic Reforming ◽  
Aqueous Phase Reforming ◽  
Production Of Hydrogen ◽  
Interesting Approach ◽  
Reforming Reactions

The growing demand for energy production highlights the shortage of traditional resources and the related environmental issues. The adoption of bioalcohols (i.e., alcohols produced from biomass or biological routes) is progressively becoming an interesting approach that is used to restrict the consumption of fossil fuels. Bioethanol, biomethanol, bioglycerol, and other bioalcohols (propanol and butanol) represent attractive feedstocks for catalytic reforming and production of hydrogen, which is considered the fuel of the future. Different processes are already available, including steam reforming, oxidative reforming, dry reforming, and aqueous-phase reforming. Achieving the desired hydrogen selectivity is one of the main challenges, due to the occurrence of side reactions that cause coke formation and catalyst deactivation. The aims of this review are related to the critical identification of the formation of carbon roots and the deactivation of catalysts in bioalcohol reforming reactions. Furthermore, attention is focused on the strategies used to improve the durability and stability of the catalysts, with particular attention paid to the innovative formulations developed over the last 5 years.

scholarly journals Mathematical modeling and optimization of semi-regenerative catalytic reforming of naphtha

2021 ◽  
Vol 76 ◽  
pp. 64
Author(s):  
Emilia Ivanchina ◽  
Ekaterina Chernyakova ◽  
Inna Pchelintseva ◽  
Dmitry Poluboyartsev
Keyword(s):  
Octane Number ◽  
Catalyst Deactivation ◽  
Formation Rate ◽  
Coke Formation ◽  
Space Velocity ◽  
Catalyst Stability ◽  
Hydrocarbon Mixture ◽  
Catalytic Reforming ◽  
Modeling And Optimization ◽  
Petroleum Refineries

Catalytic naphtha reforming is extensively applied in petroleum refineries and petrochemical industries to convert low-octane naphtha into high-octane gasoline. Besides, this process is an important source of hydrogen and aromatics obtained as side products. The bifunctional Pt-catalysts for reforming are deactivated by coke formation during an industrial operation. This results to a reduction in the yield and octane number. In this paper modeling and optimization of a semi-egenerative catalytic reforming of naphtha is carried out considering catalyst deactivation and a complex multicomponent composition of a hydrocarbon mixture. The mathematical model of semi-egenerative catalytic reforming considering coke formation process was proposed. The operating parameters (yield, octane number, activity) for different catalysts were predicted and optimized. It was found that a decrease in the pressure range from 1.5 to 1.2 MPa at the temperature 478–481 °C and feedstock space velocity equal to 1.4–1 h induces an increase in the yield for 1–2 wt.% due to an increase in the aromatization reactions rate and a decrease in the hydrocracking reactions rate depending on the feedstock composition and catalyst type. It is shown that the decrease in pressure is limited by the requirements for the catalyst stability due to the increase in the coke formation rate. The criterion of optimality is the yield, expressed in octanes per tons.

scholarly journals Analysis and Model-Based Description of the Total Process of Periodic Deactivation and Regeneration of a VOx Catalyst for Selective Dehydrogenation of Propane

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1374
Author(s):  
Andreas Brune ◽  
Andreas Seidel-Morgenstern ◽  
Christof Hamel
Keyword(s):  
Catalyst Deactivation ◽  
Process Development ◽  
Coke Formation ◽  
Fixed Bed ◽  
Reaction Network ◽  
Fixed Bed Reactor ◽  
Side Reactions ◽  
Model Based ◽  
Total Process

This study intends to provide insights into various aspects related to the reaction kinetics of the VOx catalyzed propane dehydrogenation including main and side reactions and, in particular, catalyst deactivation and regeneration, which can be hardly found in combination in current literature. To kinetically describe the complex reaction network, a reduced model was fitted to lab scale experiments performed in a fixed bed reactor. Additionally, thermogravimetric analysis (TGA) was applied to investigate the coking behavior of the catalyst under defined conditions considering propane and propene as precursors for coke formation. Propene was identified to be the main coke precursor, which agrees with results of experiments using a segmented fixed bed reactor (FBR). A mechanistic multilayer-monolayer coke growth model was developed to mathematically describe the catalyst coking. Samples from long-term deactivation experiments in an FBR were used for regeneration experiments with oxygen to gasify the coke deposits in a TGA. A power law approach was able to describe the regeneration behavior well. Finally, the results of periodic experiments consisting of several deactivation and regeneration cycles verified the long-term stability of the catalyst and confirmed the validity of the derived and parametrized kinetic models for deactivation and regeneration, which will allow model-based process development and optimization.

scholarly journals Catalyst Stability—Bottleneck of Efficient Catalytic Pyrolysis

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 265
Author(s):  
Jacek Grams ◽  
Agnieszka M. Ruppert
Keyword(s):  
Lignocellulosic Biomass ◽  
Alternative Fuels ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Catalyst Stability ◽  
Engine Fuel ◽  
Lignocellulosic Feedstock ◽  
Bio Oil ◽  
The Stability ◽  
Direct Use

The pyrolysis of lignocellulosic biomass is one of the most promising methods of alternative fuels production. However, due to the low selectivity of this process, the quality of the obtained bio-oil is usually not satisfactory and does not allow for its direct use as an engine fuel. Therefore, there is a need to apply catalysts able to upgrade the composition of the mixture of pyrolysis products. Unfortunately, despite the increase in the efficiency of the thermal decomposition of biomass, the catalysts undergo relatively fast deactivation and their stability can be considered a bottleneck of efficient pyrolysis of lignocellulosic feedstock. Therefore, solving the problem of catalyst stability is extremely important. Taking that into account, we presented, in this review, the most important reasons for catalyst deactivation, including coke formation, sintering, hydrothermal instability, and catalyst poisoning. Moreover, we discussed the progress in the development of methods leading to an increase in the stability of the catalysts of lignocellulosic biomass pyrolysis and strengthening their resistance to deactivation.

scholarly journals New Development in Catalytic Reforming Process to Produce High Octane Gasoline

2014 ◽  
Vol 5 (1) ◽  
pp. 223-244
Author(s):  
Khalid A. Sukkar ◽  
Hayam M. Abd Al-Raheem ◽  
Layth S. Sabry ◽  
Lattif A. Resym
Keyword(s):  
Coke Formation ◽  
Space Velocity ◽  
Operating Conditions ◽  
Catalyst Stability ◽  
Internal Diameter ◽  
External Diameter ◽  
Operating Pressure ◽  
Catalytic Reforming ◽  
Weight Percentage ◽  
High Octane

    In this work, improved catalytic reforming reaction was carried out through using reaction promoters Sn, In and Ge. Four types of catalysts were prepared: Pt/HY, Pt-Sn/HY, and Pt-Sn-In/HY, and Pt-Sn-Ge/HY. The weight percentage of metals were 0.5 % for Pt and 0.1% for each of  Sn, In and Ge.    The performances of catalysts (activity, selectivity and catalyst stability) were studied using Iraqi heavy naphtha  of Al-Dura refinery (Baghdad) as feedstock. The catalytic reforming unit consisted of a vertical tubular stainless steel reactor of 20mm internal diameter, 30 mm external diameter and 680 mm height. The operating pressure was atmospheric, and the operating temperatures varied between   425 to 525oC.  For all experimental runs: the weight hourly space velocity WHSV =2, the catalyst amount = 50 g, and H2/HC ratio =3.    The results showed that the best reforming temperature over all four types of prepared catalysts was 475 oC  which gave the highest conversion of heavy naphtha to high octane products (aromatics and branched  isomers). It was concluded that the trimetallic catalyst Pt-Sn-In/HY, and Pt-Sn-Ge/HY show high selectivity to desired reforming products with 91.5% and 85% respectively. On the other hand, the Pt-Sn/HY and Pt/HY, catalysts show slectivities of 79% and 74% respectively.    The results indicated a clear increase in catalyst stability with high resistance to coke formation for catalysts promoted with In and Ge as a third metal. Also, it was noted that the production  of aromatics and isomers  are  increased  for both types of trimetallic catalysts Pt-Sn-In/HY, and Pt-Sn-Ge/HY under the same operating conditions.

An analytical microscopic study of metals in fluidized catalytic cracking catalyst

1986 ◽  
Vol 44 ◽  
pp. 854-855
Author(s):  
Clifford S. Rainey
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Catalytic Cracking ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Acid Sites ◽  
Y Zeolite ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
High Regeneration

The spatial distribution of V and Ni deposited within fluidized catalytic cracking (FCC) catalyst is studied because these metals contribute to catalyst deactivation. Y zeolite in FCC microspheres are high SiO2 aluminosilicates with molecular-sized channels that contain a mixture of lanthanoids. They must withstand high regeneration temperatures and retain acid sites needed for cracking of hydrocarbons, a process essential for efficient gasoline production. Zeolite in combination with V to form vanadates, or less diffusion in the channels due to coke formation, may deactivate catalyst. Other factors such as metal "skins", microsphere sintering, and attrition may also be involved. SEM of FCC fracture surfaces, AEM of Y zeolite, and electron microscopy of this work are developed to better understand and minimize catalyst deactivation.

Catalysts for hydrogenation of CO2 into components of motor fuels

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.

scholarly journals TiO2 Nanowires with Doped g-C3N4 Nanoparticles for Enhanced H2 Production and Photodegradation of Pollutants

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 254
Author(s):  
Liushan Jiang ◽  
Fanshan Zeng ◽  
Rong Zhong ◽  
Yu Xie ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Environmental Governance ◽  
Fossil Fuels ◽  
H2 Production ◽  
Tio2 Nanowires ◽  
Photocatalytic Ability ◽  
Production Of Hydrogen ◽  
Growth Method ◽  
Renewable Hydrogen ◽  
Degradation Of Pollutants

With the rapid consumption of fossil fuels, along with the ever-increasing environmental pollution, it is becoming a top priority to explore efficient photocatalysts for the production of renewable hydrogen and degradation of pollutants. Here, we fabricated a composite of g-C3N4/TiO2 via an in situ growth method under the conditions of high-temperature calcination. In this method, TiO2 nanowires with a large specific surface area could provide enough space for loading more g-C3N4 nanoparticles to obtain C3N4/TiO2 composites. Of note, the g-C3N4/TiO2 composite could effectively photocatalyze both the degradation of several pollutants and production of hydrogen, both of which are essential for environmental governance. Combining multiple characterizations and experiments, we found that the heterojunction constructed by the TiO2 and g-C3N4 could increase the photocatalytic ability of materials by prompting the separation of photogenerated carriers. Furthermore, the photocatalytic mechanism of the g-C3N4/TiO2 composite was also clarified in detail.

scholarly journals Catalytic Hot Gas Cleanup of Biomass Gasification Producer Gas via Steam Reforming Using Nickel-Supported Clay Minerals

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1875
Author(s):  
Prashanth Reddy Buchireddy ◽  
Devin Peck ◽  
Mark Zappi ◽  
Ray Mark Bricka
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Steam Reforming ◽  
Catalyst Deactivation ◽  
Nickel Content ◽  
Coke Formation ◽  
Biomass Gasification ◽  
Supported Nickel Catalyst ◽  
Fuel Gas ◽  
Removal Efficiencies

Amongst the issues associated with the commercialization of biomass gasification, the presence of tars has been one of the most difficult aspects to address. Tars are an impurity generated from the gasifier and upon their condensation cause problems in downstream equipment including plugging, blockages, corrosion, and major catalyst deactivation. These problems lead to losses of efficiency as well as potential maintenance issues resulting from damaged processing units. Therefore, the removal of tars is necessary in order for the effective operation of a biomass gasification facility for the production of high-value fuel gas. The catalytic activity of montmorillonite and montmorillonite-supported nickel as tar removal catalysts will be investigated in this study. Ni-montmorillonite catalyst was prepared, characterized, and tested in a laboratory-scale reactor for its efficiency in reforming tars using naphthalene as a tar model compound. Efficacy of montmorillonite-supported nickel catalyst was tested as a function of nickel content, reaction temperature, steam-to-carbon ratio, and naphthalene loading. The results demonstrate that montmorillonite is catalytically active in removing naphthalene. Ni-montmorillonite had high activity towards naphthalene removal via steam reforming, with removal efficiencies greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first-order kinetics and was found to be 84.5 kJ/mole in accordance with the literature. Long-term activity tests were also conducted and showed that the catalyst was active with naphthalene removal efficiencies greater than 95% maintained over a 97-h test period. A little loss of activity was observed with a removal decrease from 97% to 95%. To investigate the decrease in catalytic activity, characterization of fresh and used catalyst samples was performed using thermogravimetric analysis, transmission electron microscopy, X-ray diffraction, and surface area analysis. The loss in activity was attributed to a decrease in catalyst surface area caused by nickel sintering and coke formation.

Continuous aqueous phase reforming of wastewater streams: A catalyst deactivation study

Fuel ◽  
2021 ◽  
Vol 305 ◽  
pp. 121506
Author(s):  
A.S. Oliveira ◽  
T. Cordero-Lanzac ◽  
J.A. Baeza ◽  
L. Calvo ◽  
J.J. Rodriguez ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Catalyst Deactivation ◽  
Aqueous Phase Reforming

scholarly journals Efficiency of using heteropoly compounds of the type (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O as catalysts for the production of ethylene

2019 ◽  
Vol 60 (11) ◽  
pp. 85-92
Author(s):  
Nikita A. Panurin ◽  
◽  
Natalya Yu. Isaeva ◽  
Ekaterina B. Markova ◽  
Tatiana F. Sheshko ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Fluorescence Analysis ◽  
Heteropoly Compound ◽  
Cascade Reactions ◽  
Environmental Benefits ◽  
Heteropoly Compounds ◽  
X Ray ◽  
Cell Parameters

Carrying out heterogeneous acid catalysis with the use of heteropoly compounds has received considerable attention due to the great economic and environmental benefits. In spite of this, its industrial application is limited as there are difficulties in catalyst regeneration (settling) caused by its relatively low thermal stability. The aim of present work was to search and select catalysts related to the class of heteropoly compounds for propane cracking, to test the selectivity of the prosses as well as to discuss possible approaches for solving the problem of catalyst deactivation, that can contribute to achieve stable characteristics of solid heteropoly catalysts. Among these approaches are: the development of new catalysts with high thermal stability, the modification of catalysts to promote coke combustion, the inhibition of coke formation on heteropoly compound catalysts during the process, carrying out the reactions in supercritical media and also the cascade reactions using a multifunctional heteropoly catalyst. The obtained catalyst was also studied by physicochemical methods to get deep knowledge about which features of these compounds influence on the catalytic activity. A highly active and selective catalyst for ammonium octomolybdenocobaltate(II) ammonium (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O was synthesized for cracking associated petroleum gases. The qualitative, quantitative, and structural composition as well as the specific surface area of the obtained catalyst was established by the methods of X-ray diffraction, X-ray phase and fluorescence analysis. It was revealed that ammonium octomolybdenocobaltate(II) crystallizes in a triclinic syngony with cell parameters: а = 8.6292(9) Å b = 9.4795(10) Å c = 12.2071(13) Å α = 104.326(2)° β = 109.910(2)° γ = 100.820(2)°.

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