A review on the microwave-assisted pyrolysis technique
TL;DR: In this paper, the effectual parameters of the microwave-assisted pyrolysis process and advantages of this technique have been summarized and concluded that microwave assisted technology is an effectual method to reduce the reaction time and increase the quality of value-added products from different kinds of feedstocks.
Abstract: Pyrolysis is a promising bioconversion technique for energy recovery, waste management, and converting biomass into useful energy products which has attracted considerable attention during the past decades. Char/carbonaceous residue, bio-oil, and syngas are the three main products of the pyrolysis process. The pyrolysis technique is one of the major barriers for large-scale commercialization of this method. This study strives to extensively review the recent work on microwave-assisted technology applied to the pyrolysis process as a way of cost reduction. The fundamentals of microwave irradiation and a brief background of pyrolysis are presented. Additionally, biomass resources which can be the raw material for pyrolysis process have been categorized and reviewed in this paper. The effectual parameters of the microwave-assisted pyrolysis process and advantages of this technique have been summarized. It is concluded that microwave-assisted technology is an effectual method to reduce the pyrolysis reaction time and increases the quality of value-added products from different kinds of feedstocks. In addition, this technique can overcome the needs of feedstock shredding and improves the quality of heating as well. Therefore, it can be a suitable method for decreasing the pyrolysis processing cost and a pathway out of poverty for developing countries.
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TL;DR: In this paper, a general summary of the properties of pyrolytic products and their analysis methods is given, as well as a review of the parameters that affect the process and a summary of current state of the art.
Abstract: Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.
1,379 citations
TL;DR: In this paper, the effect of pyrolysis process parameters on the production of biochar through biochar of biomass is discussed and a comparison between the existing techniques is established in the present work.
Abstract: Biomass is considered to have potential to be used as an alternative energy source. High carbon content present in biomass converts it into high energy biochar on thermochemical treatment. Among few well established thermochemical technologies for the treatment of biomass and biogenic waste to produce high energy char along with oil and gaseous yield, pyrolysis is the most studied and discussed technique in the recent past. A comparison between the existing techniques is established in the present work. Production of char from the biomass and biogenic wastes is reviewed and it was found that yield of the biochar depends upon the biomass composition like moisture content and presence of cellulose or lignin. Pyrolysis product distribution and their quality strongly depend upon the process parameters. Different biomasses which can be used as raw material in pyrolysis are also reviewed and categorized depending upon their source. Pyrolysis process parameters such as temperature, heating rate, residence time etc. also influence the biochar yield. This study discusses the effect of these process parameters on the production of biochar through pyrolysis of biomass.
944 citations
TL;DR: In this paper, the current scenario of the plastic recycling technology is reviewed in order to provide the reader with an in-depth analysis with respect to the pyrolysis of plastic waste as obtained in the current recycling technology.
Abstract: Due to the depleting fossil fuel sources such as crude oil, natural gas, and coal, the present rate of economic growth is unsustainable. Therefore, many sources of renewable energy have been exploited, but the potentials of some other sources such as plastics waste are yet to be fully developed as full scale economic activity. Development and modernization have brought about a huge increase in the production of all kinds of plastic commodities, which directly or indirectly generate waste due to their wide range of applications coupled with their versatility of types and relatively low cost. The current scenario of the plastic recycling technology is reviewed in this paper. The aim is to provide the reader with an in-depth analysis with respect to the pyrolysis of plastic waste as obtained in the current recycling technology. As the calorific value of the plastics is comparable to that of hydrocarbon fuel, production of fuel from plastic waste would provide a good opportunity to utilize the waste as a better alternative to dumpsites. Different techniques of converting plastics waste into fuel including thermal and catalytic pyrolysis, microwave-assisted pyrolysis and fluid catalytic cracking are discussed in detail. The co-pyrolysis of plastics waste with biomass is also highlighted. Thus, an attempt was made to address the problem of plastic waste disposal as a partial replacement of the depleting fossil fuel with the hope of promoting a sustainable environment.
439 citations
TL;DR: A comprehensive review of the progress in biomass torrefaction technologies is provided in this article, where the authors perform an in-depth literature survey and identify a current trend in practical tor-refaction development and environmental performance.
357 citations
TL;DR: In this article, the performance data of metal oxide thin film electrodes by microwave-assisted as an inexpensive, quick and versatile technique is presented for supercapacitor performance data, and metal oxide films will continue to play a major role in supercapACitor technology and are expected to considerably increase the capabilities of these devices in near future.
355 citations
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TL;DR: A review of the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrotechnics, can be found in this paper.
Abstract: Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to liquid fuels and chemicals since the oil crisis in mid-1970s. This review focuses on the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrolysis. Virtually any form of biomass can be considered for fast pyrolysis. Most work has been performed on wood, because of its consistency and comparability between tests. However, nearly 100 types of biomass have been tested, ranging from agricultural wastes such as straw, olive pits, and nut shells to energy crops such as miscanthus and sorghum. Forestry wastes such as bark and thinnings and other solid wastes, including sewage sludge and leather wastes, have also been studied. In this review, the main (although not exclusive) emphasis has been given to wood. The literature on woo...
4,988 citations
TL;DR: In this paper, an updated review on fast pyrolysis of biomass for production of a liquid usually referred to as bio-oil is provided, including the major reaction systems.
Abstract: This paper provides an updated review on fast pyrolysis of biomass for production of a liquid usually referred to as bio-oil. The technology of fast pyrolysis is described including the major reaction systems. The primary liquid product is characterised by reference to the many properties that impact on its use. These properties have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. Of particular note is the increasing diversity of methods and catalysts and particularly the complexity and sophistication of multi-functional catalyst systems. It is also important to see more companies involved in this technology area and increased take-up of evolving upgrading processes. © 2011 Elsevier Ltd.
3,727 citations
TL;DR: This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.
Abstract: Although fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied to a reaction vessel in a focused manner. The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction. In the past few years, heating and driving chemical reactions by microwave energy has been an increasingly popular theme in the scientific community. This nonclassical heating technique is slowly moving from a laboratory curiosity to an established technique that is heavily used in both academia and industry. The efficiency of "microwave flash heating" in dramatically reducing reaction times (from days and hours to minutes and seconds) is just one of the many advantages. This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.
3,044 citations