Production and utilization of biochar: A review Cha, Jin Sun; Park, Sung Hoon; Jung, Sang-Chul ...
Journal of industrial and engineering chemistry (Seoul, Korea),
08/2016, Letnik:
40
Journal Article
Recenzirano
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Biochar produced during the thermochemical decomposition of biomass not only reduces the amount of carbon emitted into the atmosphere, but it is also an environment-friendly ...replacement for activated carbon and other carbon materials. In this review paper, researches on biochar are discussed in terms of production method and application. Different processes for biochar production, such as pyrolysis, gasification, hydrothermal carbonization, etc., are compared. Physical and chemical activation methods used to improve the physicochemical properties of biochar and their effects are also compared. Various environmental application fields of biochar including adsorption (for water pollutants and for air pollutants), catalysis (for syngas upgrading, for biodiesel production, and for air pollutant treatment), and soil conditioning are discussed. Recent research trend of biochar in other applications, such as fuel cell, supercapacitor, and hydrogen storage, is also reviewed.
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•The production of green H2 from biomass valorization by gasification was explained.•The gaseous product of gasification is intensely affected by experimental conditions.•Steam has ...been known as the most efficient gasifying agent for the H2 production.•Functional mechanism of catalyst affects the gasification efficiency and H2 yield.•Technical and economic obstacles should be solved for gasification commercialization.
Green and sustainable hydrogen from biomass gasification processes is one of the promising ways to alternate fossil fuels-based hydrogen production. First off, an overview of green hydrogen generation from biomass gasification processes is presented and the corresponding possible gasification reactions and the effect of respective experimental criteria are explained in detail. In addition, a comprehensive explanation of the catalytic effect on tar reduction and hydrogen generation via catalytic gasification is presented regarding the functional mechanisms of various types of catalysts. Furthermore, the commercialization aspects, the associated technical challenges and barriers, and the prospects of a biomass gasification process for green hydrogen generation are discussed. Finally, this comprehensive review provides the related advancements, challenges, and great insight of biomass gasification for the green hydrogen generation to realize a sustainable hydrogen society via biomass valorization.
The unique properties of organic photovoltaics (OPVs) offer great promise in emerging applications such as wearable electronics or the Internet of Things. For their successful utilization, OPV ...operation should be designed for versatile irradiation circumstances in addition to solar light since they should be capable of providing electric power when there is no sunlight or when they operate indoors. Here, a quaternary OPV (Q‐OPV) as a semitransparent, colorful energy platform that operates efficiently under both solar and artificial light irradiation is demonstrated. The experimentally optimized Q‐OPV shows a broadened spectral response and improved charge transport process with suppressed recombination, thereby providing high output powers that are sufficient to autonomously operate low‐power electronic devices. In addition, the Q‐OPV benefits from improved morphological stability with a reduced driving force for grain growth by the increased entropy in the quaternary blend system. The important features of the Q‐OPV platform such as semitransparency, high tolerance to film thickness, and color codability, while pursuing the improved performance and thermal durability, further open new opportunities as an all‐day (24/7/365) power generator in broad practical applications.
Quaternary blend organic photovoltaics (Q‐OPVs) exhibit efficient operation under diverse irradiation conditions and improved thermal durability with suppressed morphological evolution during operation. The unique properties of the Q‐OPVs such as semitransparency, high film thickness tolerance, and color codability expand their applicability to emerging energy systems, which operate autonomously by any incident light all day, even when there is no sunlight.
Air pollution, particularly for toxic and harmful compounds to humans and the environment, has aroused increasing public concerns. Among air pollutants, volatile organic compounds (VOCs) are the main ...sources of air pollution. Many attempts have been made to control VOCs using catalysts, plasma, photolysis, and adsorption. Among them, oxidative catalysis by noble metals or transition metal oxides is considered one of the most feasible and effective methods to control VOCs. This paper reviews the experimental achievements on the abatement of VOCs using noble metals, transition metals and modified metal oxide catalysts. Although the catalytic degradation of VOCs appears to be feasible, there are unavoidable problems when only catalysis treatments are applied to the field. Therefore, catalysts including hybrid processes are developed to improve the removal efficiency of VOCs. This review addresses new hybrid treatments to remove VOCs using catalysts, including hybrid treatment combined with plasma, photolysis, and adsorption. The mechanism of the oxidation of VOCs by catalysts is explained by adsorption-desorption principles, such as the Langmuir-Hinshelwood, Eley-Rideal, and Mars-van-Krevelen mechanisms. A π-backbonding interaction between unsaturated compounds and transition metals is introduced to better understand the mechanism of VOC removals. Finally, several factors affecting the catalytic activities, such as support, component ratio, preparation method, metal loading, and deactivation factor, are discussed.
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•Catalytic degradation of VOCs was introduced.•New hybrid treatments to remove VOCs using catalysts were addressed.•The mechanism of the oxidation of VOCs by a catalyst was suggested.•Several factors affecting the catalytic activities were discussed.
The severity of the coronavirus disease (COVID-19) is associated with various comorbidities. However, no studies have yet demonstrated the potential risk of respiratory failure and mortality in ...COVID-19 patients with pre-existing asthma. We selected 7272 adult COVID-19 patients from the Korean Health Insurance Review and Assessment COVID-19 database for this nationwide retrospective cohort study. Among these, 686 patients with asthma were assessed by their severities and evaluated by the clinical outcome of COVID-19 compared to patients without asthma. Of 7272 adult COVID-19 patients, 686 with asthma and 6586 without asthma were compared. Asthma was not a significant risk factor for respiratory failure or mortality among all COVID-19 patients (odds ratio OR = 0.99, P = 0.997 and OR = 1.06, P = 0.759) after adjusting for age, sex, and the Charlson comorbidity score. However, a history of acute exacerbation (OR = 2.63, P = 0.043) was significant risk factors for death among COVID-19 patients with asthma. Asthma is not a risk factor for poor prognosis of COVID-19. However, asthma patients who had any experience of acute exacerbation in the previous year before COVID-19 showed higher COVID-19-related mortality, especially in case of old age and male sex.
Underlying chronic respiratory disease may be associated with the severity of coronavirus disease 2019 (COVID-19). This study investigated the impact of chronic obstructive pulmonary disease (COPD) ...on the risk for respiratory failure and mortality in COVID-19 patients. A nationwide retrospective cohort study was conducted in 4610 patients (≥ 40 years old) infected with COVID-19 between January 20 and May 27, 2020, using data from the Ministry of Health and Welfare and Health Insurance Review and Assessment Service in Korea. The clinical course and various clinical features were compared between COPD and non-COPD patients, and the risks of respiratory failure and all-cause mortality in COPD patients were analyzed using a multivariate logistic regression model. Among 4610 COVID-19 patients, 4469 (96.9%) and 141 (3.1%) were categorized into the non-COPD and COPD groups, respectively. The COPD group had greater proportions of older (≥ 60 years old) (78.0% vs. 45.2%, P < 0.001) and male (52.5% vs. 36.6%, P < 0.001) patients than the non-COPD group. Relatively greater proportions of patients with COPD received intensive critical care (7.1% vs. 3.7%, P = 0.041) and mechanical ventilation (5.7% vs. 2.4%, P = 0.015). Multivariate analyses showed that COPD was not a risk factor for respiratory failure but was a significant independent risk factor for all-cause mortality (OR = 1.80, 95% CI 1.11-2.93) after adjustment for age, sex, and Charlson Comorbidity Index score. Among COVID-19 patients, relatively greater proportions of patients with COPD received mechanical ventilation and intensive critical care. COPD is an independent risk factor for all-cause mortality in COVID-19 patients in Korea.
The hydrodeoxygenation of a model compound of lignin-derived bio-oil, guaiacol, which can be obtained from the pyrolysis of biomass to bio-oil, has attracted considerable research attention because ...of its huge potential as a substitute for conventional fuels. In this study, platinum-loaded HY zeolites (Pt/HY) with different Si/Al molar ratios were used as catalysts for the hydrodeoxygenation of guaiacol, anisole, veratrole, and phenol to a range of hydrocarbons, such as cyclohexane. The cyclohexane (major product) yield increased with increasing number of acid sites. To produce bio-oil with the maximum level of cyclohexane and alkylated cyclohexanes, which would be suitable as a substitute for conventional transportation fuels, the Si/Al molar ratio should be optimized to balance the Pt particle-induced hydrogenation with acid site-induced methyl group transfer. The fuel properties of real bio-oil derived from the fast pyrolysis of cork oak was improved using the Pt/HY catalyst.
In this study, wasted mask is chosen as a pyrolysis feedstock whose generation has incredibly increased these days due to COVID-19. We suggest a way to produce value-added chemicals (e.g., aromatic ...compounds) from the mask with high amounts through catalytic fast pyrolysis (CFP). To this end, the effects of zeolite catalyst properties on the upgradation efficiency of pyrolytic products produced from pyrolysis of wasted mask were investigated. The compositions and yields of pyrolytic gases and oils were characterized as functions of pyrolysis temperature and the type of zeolite catalyst (HBeta, HY, and HZSM-5), including the mesoporous catalyst of Al-MCM-41. The mask was pyrolyzed in a fixed bed reactor, and the pyrolysis gases evolved in the reactor was routed to a secondary reactor inside which the zeolite catalyst was loaded. It was chosen 550 °C as the CFP temperature to compare the catalyst performance for the production of benzene, toluene, ethylbenzene, and xylene (BTEX) because this temperature gave the highest oil yield (80.7 wt%) during the non-catalytic pyrolysis process. The large pore zeolite group of HBeta and HY led to 134% and 67% higher BTEX concentrations than HZSM-5, respectively, likely because they had larger pores, higher surface areas, and higher acid site density than the HZSM-5. This is the first report of the effect of zeolite characteristics on BTEX production via CFP.
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•Catalytic pyrolysis for transforming COVID-19 mask to BTEX was investigated.•HZSM-5 was not effective at making BTEX from the mask due to small pores.•Big enough pores allowing branched hydrocarbons enter and acidity are required to transform the mask to BTEX.
Effective valorization of COVID-19 mask to value-added chemicals like BTEX via catalytic pyrolysis is highly associated with large pores and high acid site density of zeolite.
•The hydrogen production from water electrolysis is very efficient.•The metal based single-layered atomic dispersed electrocatalyst are introduced.•Noble metal free nanostructured metal component ...electrocatalysts are explained.•Graphene based electrocatalysts are compared.•Bifunctional electrodes using metal sulfides and phosphides are introduced.
Hydrogen is one of the most promising alternative energy resources of fossil fuels. Among the many ways to generate hydrogen gas, electrochemical water splitting is more feasible and renewable. Compared to processes using solar energy for a specific geological environment or thermochemical decomposition at high temperatures, the electrocatalysis of water can produce hydrogen without the restriction of geological conditions and scale-up facilities. Water is one of the most renewable and sustainable resources to obtain hydrogen. On the other hand, water splitting into hydrogen and oxygen is thermodynamically unfavorable under the atmospheric condition. Therefore, novel materials are needed to produce hydrogen from water splitting using electrocatalysts. Recently, various state-of-the-art technologies and catalysts have been developed in the electrocatalysis of water to produce hydrogen. Among the litany of novel materials, according to the preparation method and morphology of electrocatalysts, the hydrogen production efficiency from water splitting shows great differences. This paper recently reported efficient electrocatalysts for water splitting using multi-component catalysts composed of several metals, organic polymer, metal sulfides, and metal phosphides. In addition, the essential principles for an investigation regarding more efficient hybrid electrocatalysts for water splitting as a renewable and sustainable hydrogen producing method can be determined.
•Catalytic copyrolysis of yellow poplar and high density polyethylene was performed.•Torrefaction of yellow poplar produced large amounts of aromatics.•HZSM-5 produced larger amounts of aromatics ...than Al-MCM-41.•In-situ catalytic co-pyrolysis was more efficient than ex-situ reaction.
The catalytic pyrolysis of lignocellulosic biomass with aluminosilicate catalysts is a promising method for the direct production of liquid hydrocarbon fuels consisting mainly of aromatic compounds (e.g., benzene, toluene, and xylenes). On the other hand, the economic and commercial viability of this process is limited by the low yields of aromatic hydrocarbons. In this study, the effects of biomass torrefaction, co-feeding of plastic wastes, their combination, and the catalytic upgrading mode (in-situ vs ex-situ) on the aromatic formation efficiency during the catalytic pyrolysis of yellow poplar were evaluated systematically to maximize the production of aromatic hydrocarbons. Two representative catalysts for catalytic pyrolysis (i.e., microporous HZSM-5 and mesoporous Al-MCM-41) were used in this case study. The torrefaction of yellow poplar led to the enhanced production of aromatic hydrocarbons in the catalytic co-pyrolysis of yellow poplar and high-density polyethylene over both catalysts. The experimental yields of aromatic hydrocarbons from the catalytic co-pyrolysis of torrefied yellow poplar and high-density polyethylene were also higher than their theoretical yields, highlighting the synergistic aromatic formation by the interaction of torrefied yellow poplar and high-density polyethylene. Between the two catalysts, microporous HZSM-5 exhibited much higher activity for aromatic production from catalytic co-pyrolysis owing to its strong acidity and appropriate pore structure. Compared to ex-situ catalytic co-pyrolysis, the in-situ catalytic co-pyrolysis of torrefied yellow poplar and high-density polyethylene produced larger amounts of aromatic hydrocarbons due to the more effective contact between the pyrolysis vapors and HZSM-5.
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