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 Mechanistic Insights into Hydrodeoxygenation of Acetone over Mo/HZSM-5 Bifunctional Catalyst for the Production of Hydrocarbons

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 53
Author(s):  
Kai Miao ◽  
Tan Li ◽  
Jing Su ◽  
Cong Wang ◽  
Kaige Wang
Keyword(s):  
Hydrogen Pressure ◽  
Catalyst Deactivation ◽  
Catalyst Activity ◽  
Coke Formation ◽  
Bifunctional Catalyst ◽  
Acid Sites ◽  
Coke Deposition ◽  
Enhanced Production ◽  
Bio Oil ◽  
Catalytic Hydropyrolysis

Catalytic hydropyrolysis via the introduction of external hydrogen into catalytic pyrolysis process using hydrodeoxygenation catalysts is one of the major approaches of bio-oil upgrading. In this study, hydrodeoxygenation of acetone over Mo/HZSM-5 and HZSM-5 were investigated with focus on the influence of hydrogen pressure and catalyst deactivation. It is found that doped MoO3 could prolong the catalyst activity due to the suppression of coke formation. The influence of hydrogen pressure on catalytic HDO of acetone was further studied. Hydrogen pressure of 30 bar effectively prolonged catalyst activity while decreased the coke deposition over catalyst. The coke formation over the HZSM-5 and Mo/HZSM-5 under 30 bar hydrogen pressure decreased 66% and 83%, respectively, compared to that under atmospheric hydrogen pressure. Compared to the test with the HZSM-5, 35% higher yield of aliphatics and 60% lower coke were obtained from the Mo/HZSM-5 under 30 bar hydrogen pressure. Characterization of the spent Mo/HZSM-5 catalyst revealed the deactivation was mainly due to the carbon deposition blocking the micropores and Bronsted acid sites. Mo/HZSM-5 was proved to be potentially enhanced production of hydrocarbons.

scholarly journals Upgrading of Oils from Biomass and Waste: Catalytic Hydrodeoxygenation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1381
Author(s):  
Mai Attia ◽  
Sherif Farag ◽  
Jamal Chaouki
Keyword(s):  
Microwave Heating ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
Coke Formation ◽  
High Viscosity ◽  
High Oxygen ◽  
Conventional Heating ◽  
Pyrolysis Oil ◽  
High Oxygen Content ◽  
Bio Oil

The continuous demand for fossil fuels has directed significant attention to developing new fuel sources to replace nonrenewable fossil fuels. Biomass and waste are suitable resources to produce proper alternative fuels instead of nonrenewable fuels. Upgrading bio-oil produced from biomass and waste pyrolysis is essential to be used as an alternative to nonrenewable fuel. The high oxygen content in the biomass and waste pyrolysis oil creates several undesirable properties in the oil, such as low energy density, instability that leads to polymerization, high viscosity, and corrosion on contact surfaces during storage and transportation. Therefore, various upgrading techniques have been developed for bio-oil upgrading, and several are introduced herein, with a focus on the hydrodeoxygenation (HDO) technique. Different oxygenated compounds were collected in this review, and the main issue caused by the high oxygen contents is discussed. Different groups of catalysts that have been applied in the literature for the HDO are presented. The HDO of various lignin-derived oxygenates and carbohydrate-derived oxygenates from the literature is summarized, and their mechanisms are presented. The catalyst’s deactivation and coke formation are discussed, and the techno-economic analysis of HDO is summarized. A promising technique for the HDO process using the microwave heating technique is proposed. A comparison between microwave heating versus conventional heating shows the benefits of applying the microwave heating technique. Finally, how the microwave can work to enhance the HDO process is presented.

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 Chromatographic analysis of bio-oil formed in fast pyrolysis of lignocellulosic biomass

2020 ◽  
Vol 39 (1) ◽  
pp. 65-77
Author(s):  
Jacek Grams
Keyword(s):  
Lignocellulosic Biomass ◽  
Complex Structure ◽  
Fast Pyrolysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Lignocellulosic Feedstock ◽  
Temperature Decomposition ◽  
Bio Oil ◽  
Gc X Gc

AbstractFast pyrolysis of lignocellulosic biomass is one of the most promising methods of the production of renewable fuels. However, an optimization of the conditions of bio-oil production is not possible without comprehensive analysis of the composition of formed products. There are several methods for the determination of distribution of products formed during thermal decomposition of biomass with chromatography being the most versatile among them. Although, due to the complex structure of bio-oil (presence of hundreds chemical compounds with different chemical character), an interpretation of the obtained chromatograms is not an easy task. Therefore, the aim of this work is to present an application of different chromatographic methods to the analysis of the composition of the mixture of products formed in high temperature decomposition of lignocellulosic feedstock. It includes pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), two dimensional gas (GC x GC) or liquid chromatography (LC x LC) and initial fractionation of bio-oil components. Moreover, the problems connected with the analysis of bio-oils formed with the use of various fast pyrolysis reactors and capabilities of multivariate analysis are discussed.

Comparative Study on Hydrotreating of Venezuela De-Asphalted Oil: Conversion Behavior of Heteroatom Compounds and HDM Catalyst Deactivation

2014 ◽  
Vol 926-930 ◽  
pp. 320-324
Author(s):  
Tao Zhang ◽  
Shi Jie Zhou ◽  
Qiang Wei ◽  
Ting Ting Liu ◽  
Wen Wu Zhou ◽  
...  
Keyword(s):  
Catalyst Deactivation ◽  
Coke Formation ◽  
Coke Deposition ◽  
Diffusion Resistance ◽  
Second Stage ◽  
Reaction Severity ◽  
The Stability ◽  
Impurities Removal ◽  
Heteroatom Compounds

A 1000 hour hydrotreating experiment was performed to investigate the hydrotreating behavior of heteroatom compounds (first stage) and HDM catalyst deactivation (second stage) using Venezuela De-Asphalted Oil. The effect of reaction severity on impurities removal was the expected one, the deeper the hydrotreating degree, the higher the conversion of impurities. The Characterization of spent HDM catalyst shows that the content of coke deposition on spent HDM catalyst is only 4 wt% while that of metal is more than 30 wt%. Vanadium compounds in DAO with less diffusion resistance can deposit inside of the HDM catalyst grain. Lower coke formation also retard the HDM catalyst by keeping the diffusion pores and active cites. The removal of asphaltenes largely improved the stability of the HDM catalyst.

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.

Research progress on levoglucosan production via pyrolysis of lignocellulosic biomass and its effective recovery from bio-oil

2021 ◽  
Vol 9 (4) ◽  
pp. 105614
Author(s):  
Ibrahim Gbolahan Hakeem ◽  
Pobitra Halder ◽  
Mojtaba Hedayati Marzbali ◽  
Savankumar Patel ◽  
Sazal Kundu ◽  
...  
Keyword(s):  
Lignocellulosic Biomass ◽  
Research Progress ◽  
Bio Oil

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.

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