Microwave-assisted Pyrolysis Of Biomass Research Articles

Microwave-assisted pyrolysis in biomass and waste valorisation: Insights into the life-cycle assessment (LCA) and techno-economic analysis (TEA)

Microwave-assisted pyrolysis (MAP) has been perceived as a promising technology for biomass and waste conversion due to its distinctive features, including fast, even, and precise heating. This results in higher energy efficiency when compared to conventional pyrolysis via thermal heating. However, the scaling up of MAP of biomass and waste poses challenges, with investigations ongoing to uncover not only the technological aspect, but also both the environmental impacts and economic feasibility associated with this process/technology. The possible environmental impacts associated with MAP processes can be analyzed through systematic life-cycle assessment (LCA), while the economic feasibility can be evaluated via techno-economic analysis (TEA). This paper presents an overview of the current research trend in MAP and the products produced, as well as the LCA and TEA of the pyrolysis technologies. The LCA study reported a 2.5 folds reduction in energy consumption and up to 62% reduction in global warming potential. TEA study revealed that conventional pyrolysis has a greater profit for long-term assessment due to a higher maturity and less complexity technology; however, MAP may be more economically feasible in the future owing to the increased maturity and more established technology. Finally, the challenges and future perspectives for LCA and TEA in MAP are elucidated.

Exploring machine learning applications in chemical production through valorization of biomass, plastics, and petroleum resources: A comprehensive review

Machine learning (ML) is a subtype of artificial intelligence that uses a computer's ability to learn from a given set of accessible data. ML is becoming prominent in almost every business, including the domain of chemical engineering, where there have been numerous researches and investigations. This article provides a detailed overview of the use of ML in the production and characterization study of biomass, polymers, and petroleum products. Categories of ML, including classification, regression, and clustering, are also investigated to get a deeper understanding of ML. From this review, it can be concluded that ML has aided in numerous domains, such as the prediction of biomass energy, the stability of crude oil based on NMR spectroscopy, the calculation of gasoline's octane number, the estimation of fuel oil's kinematic viscosity, the classification of waste plastics, and the estimation of drilling efficiency in petroleum reservoirs, among others. Apart from this, ML has also been playing a significant role in the microwave-assisted pyrolysis of biomass, polymers, and petroleum resources. ML substantially influences chemical engineering and is especially useful for enhancing system efficiency and monitoring processes that are difficult to understand manually. Although several obstacles are associated with ML, such as black box behavior, the need for a large amount of data, and the difficulty of understanding the predictions, deploying the model in the future is uncomplicated once the learning program has been trained.

Bibliometric analysis of research progress in microwave-assisted pyrolysis of biomass during 1979–2023

Increasing the footprint of installed renewable energy capacity helps to mitigate CO2 emissions. Numerous countries have been devising strategies for harnessing various renewable sources to meet the rising demands. Solar, wind, hydro, geothermal, and biomass are a few of the renewable sources that are being used to generate electricity across the globe. Based on the nature of the source's availability, biomass is considered one of the plausible resources to generate electricity consistently. In light of this, extensive research works is being conducted to explore different approaches to convert biomass to energy. Microwave pyrolysis is one of the new approaches to convert biomass into energy. This study aims to understand the global trends in adopting micro-wave-assisted pyrolysis with the help of bibliometric analysis performed based on keyword occurrences. A total of 510 scientific contributions have been made between 1979 and 2023, addressing various aspects of microwave-assisted pyrolysis to convert biomass into energy. To gain insights into the adaptability of microwave-assisted pyrolysis, temporal growth in the total number of publications and citations has been studied. Prominent publications, top journal sources, highly contributing countries, and researchers are also identified to facilitate future research in this area. Findings suggest that attention to microwave pyrolysis is increasing by 7.59%, and China is designated as the top nation and the most frequent partner in microwave-assisted pyrolysis of biomass, followed by the United States and Malaysia. Bioresource Technology, Journal of Analytical and Applied Pyrolysis, Fuel, and Energy are popular journals focusing on microwave-assisted pyrolysis. Based on the bibliometric study of prior existing work, this study presents a road map for collaborations to conduct research on microwave-assisted pyrolysis of biomass to generate energy.

Microwave-Assisted Pyrolysis of Biomass with and without Use of Catalyst in a Fluidised Bed Reactor: A Review

Lignocellulosic biomass and waste, such as plastics, represent an abundant resource today, and they can be converted thermo-chemically into energy in a refinery. Existing research works on catalytic and non-catalytic pyrolysis performed in thermally-heated reactors have been reviewed in this text, along with those performed in microwave-heated ones. Thermally-heated reactors, albeit being the most commonly used, present various drawbacks such as superficial heating, high thermal inertia and slow response times. That is why microwave-assisted pyrolysis (MAP) appears to be a very promising technology, even if the process does present some technical drawbacks as well such as the formation of hot spots. The different types of catalysts used during the process and their impacts have also been examined in the text. More specifically, studies conducted in fluidised bed reactors (FBR) have been detailed and their advantages and drawbacks discussed. Finally, future prospects of MAP have been briefly presented.

Process intensification on co-pyrolysis of polyethylene terephthalate wastes and biomass via microwave energy: Synergetic effect and roles of microwave susceptor

The present study employs microwave (MW) energy to enhance the co-pyrolysis of polyethylene terephthalate (PET) wastes and biomass. Based on the characterization of raw materials as well as gas and liquid products, we propose a pyrolysis mechanism of PET and biomass during microwave-assisted pyrolysis (MAP). The MAP of PET-biomass blends shows a synergetic effect that the interaction between PET and biomass promotes the yields of value-added products (e.g. aromatic acids and phenols) and suppresses the generation of biphenyls and polycyclic aromatic hydrocarbons, compared to the MAP of individual biomass or plastics. Besides, the blending ratio of PET-biomass has significant effect on the formation of major liquid products. The liquid product from the MAP of PET-biomass 4:1 blends contains above 30 wt.% chain hydrocarbon that can be used as gasoline and kerosene. Moreover, we evaluate the roles of three typical MW absorbing materials during MAP, including carbon powder, ferroferric oxide (Fe3O4) and calcium oxide (CaO). Carbon powder can enlarge the yield of main products from plastics pyrolysis due to its significant dielectric loss. Apart from the MW-absorbing ability, Fe3O4 can accelerate the esterification and decarboxylation reaction; CaO can convert acids into ketones and hydrocarbons through neutralization and catalytic cracking reactions.

Microwave-assisted low-temperature biomass pyrolysis: from mechanistic insights to pilot scale

Similar to how Ne zha grows, microwave-assisted pyrolysis of biomass at low temperature firmly moves from a fundamental laboratory to a pilot scale.

Microwave-assisted catalytic fast pyrolysis coupled with microwave-absorbent of soapstock for bio-oil in a downdraft reactor

Microwave-assisted pyrolysis of biomass with HZSM-5 coupled with SiC as microwave-absorbent in a downdraft reactor is a promising method for obtaining hydrocarbon-rich bio-oil. The hydrocarbon content limits the economic and commercial viability of the bio-oil produced by pyrolysis. In this study, the effects of catalytic temperature, feedstock-to-catalyst ratio, and WHSV on the yield and composition of bio-oil are studied. In addition, this study compared the influence of downdraft reaction and updraft reaction on the yield and composition of bio-oil. Furthermore, the stability of the catalyst is studied. Catalytic temperature and feedstock-to-catalyst ratio played pivotal roles in the yield and composition of bio-oil. WHSV has minimal influence on the bio-oil yield and composition within the scope of our research. Furthermore, the optimal catalytic temperature, feedstock-to-catalyst ratio and WHSV were 400 °C, 2:1, and 72 h−1, respectively. The results illustrated that the downdraft coupled with the microwave-absorbent was conducive to the formation of aromatic hydrocarbons. The HZSM-5 performed well in five replicate experimental cycles under optimal conditions in terms of bio-oil yield and aromatic hydrocarbon yield.

Microwave-Assisted Pyrolysis of Biomass for Bio-Oil Production: A Review of the Operation Parameters

As compared with the conventional electrical heating pyrolysis, microwave-assisted pyrolysis (MAP) is more rapid and efficient due to its unique heating mechanisms. However, bio-oil production from MAP of biomass is strongly dependent on the operation parameters. Based on the recent researches, this study reviews the effects of the main operation parameters including microwave power, pyrolysis temperature, and pyrolysis time on the bio-oil yield obtained from MAP of biomass. The results show that microwave power, pyrolysis temperature, and pyrolysis time usually increase the bio-oil yield initially and decrease the bio-oil yield finally. The reported optimal microwave powers, pyrolysis temperatures, and pyrolysis times were mainly in the ranges of 300–1500 W, 400–800 °C, and 6–25 min, respectively. The mechanisms for bio-oil produced from MAP of biomass as affected by the main operation parameters were also analyzed.

Dielectric characterization of bentonite clay at various moisture contents and with mixtures of biomass in the microwave spectrum

ABSTRACTThis study assesses the potential for using bentonite as a microwave absorber for microwave-assisted biomass pyrolysis based on the dielectric properties. As bentonite is a hygroscopic material, the effect of bound water content on dielectric properties was addressed in this study. Dielectric properties of bentonite at different moisture contents were measured using a coaxial line dielectric probe and vector network analyser in the microwave frequency range from 0.2 to 4.5 GHz at room temperature. Further, dielectric properties of mixtures of bentonite with biomass were measured from 1.5 to 20 GHz as mixtures of bentonite with biomass could have microwave processing applications such as the thermochemical conversion of biomass to biofuel. Both dielectric constant and dielectric loss factor increased linearly with increasing moisture content. Measurements on biomass and bentonite mixtures show a quadratic increase in dielectric constant and loss factor with increasing bentonite content and with moisture contents ranging from 9.5% (pure bentonite) to 11.4% (pure biomass) wet basis. At 915 MHz, dielectric constant ranged from 2.0 to 6.2 and dielectric loss ranged from 0.2 to 2.7, respectively. At 2450 MHz, dielectric constant ranged from 1.8 to 5.1 and dielectric loss ranged from 0.7 to 2.6, respectively.

Conventional and microwave-assisted pyrolysis of biomass under different heating rates

Biomass was subjected to conventional and microwave pyrolysis, to determine the influence of each process on the yield and composition of the derived gas, oil and char products. The influence of pyrolysis temperature and heating rate for the conventional pyrolysis and the microwave power was investigated. Two major stages of gas release were observed during biomass pyrolysis, the first being CO/CO2 and the second one CH4/H2. This two-stage gas release was much more obvious for the conventional pyrolysis. While similar yield of liquid was obtained for both cases of conventional and microwave pyrolysis (∼46wt.%), higher gas yield was produced for the conventional pyrolysis; it is suggested that microwave pyrolysis is much faster. When the heating rate was increased, the peak release of CO and CO2 was moved to higher reaction temperature for both conventional (500°C) and microwave pyrolysis (200°C). The production of CH4 and H2 were very low at a conventional pyrolysis temperature of 310°C and microwave pyrolysis temperature of 200°C (600 and 900W). However, at higher heating rate of microwave pyrolysis, clear release of CH4 was observed. This work tentatively demonstrates possible connections and difference for biomass pyrolysis using two different heating resources (conventional and microwave heating).

Catalytic Conversion of Microwave-assisted Pyrolysis Vapors

The effect of the following catalysts: MS (Molecular sieve) 4A, Fe2O3/MS 4A, CoO/MS 4A, NiO/MS 4A, MgO/MS 4A, PtO/MS 4A, Al2O3/MS 4A, La2O3/MS 4A, Cl−/MS 3A, SO2− 4/MS 3A, Na2O/MS 3A, CaO/MS 3A, K2O/MS 3A, CoO/ZrO2, NiO/ZrO2, La2O3/ZrO2, NiO/CaO-ZrO2, Cl−/ZrO2, SO2− 4/ZrO2, Na2O/ZrO2, CaO/ZrO2, and MgO/ZrO2, on chemical profile of the products from microwave-assisted pyrolysis of biomass was studied. A microwave oven with a frequency of about 2.4 gigahertz, and a power of about 1–1.3 kilowatt was used to pyrolyze aspen (Populus tremuloides). The steam that evolved was removed from the oven and passed to a catalyst column where the temperature was controlled at about 350–600°C, and the converted vapors were then condensed to bio-oils. The chemical profiles of the bio-oils were determined using gas chromatography-mass spectrometry. Solid acids were proved to be effective catalysts to decompose pyrolysis vapors, while solid alkaline and other catalysts do not seem to affect the composition of the liquid products from microwave-assisted pyrolysis. Increasing the temperature of the catalyst bed and the ratio of catalysts to biomass adversely affected the liquid yield.

Microwave-assisted pyrolysis of biomass: Catalysts to improve product selectivity

This study was intended to evaluate the effects of catalysts on product selectivity of microwave-assisted pyrolysis of corn stover and aspen wood. Metal oxides, salts, and acids including K 2Cr 2O 7, Al 2O 3, KAc, H 3BO 3, Na 2HPO 4, MgCl 2, AlCl 3, CoCl 2, and ZnCl 2 were pre-mixed with corn stover or aspen wood pellets prior to pyrolysis using microwave heating. The thermal process produced three product fractions, namely bio-oil, gas, and charcoal. The effects of the catalysts on the fractional yields were studied. KAc, Al 2O 3, MgCl 2, H 3BO 3, and Na 2HPO 4 were found to increase the bio-oil yield by either suppressing charcoal yield or gas yield or both. These catalysts may function as a microwave absorbent to speed up heating or participate in so-called “ in situ upgrading” of pyrolytic vapors during the microwave-assisted pyrolysis of biomass. GC–MS analysis of the bio-oils found that chloride salts promoted a few reactions while suppressing most of the other reactions observed for the control samples. At 8 g MgCl 2/100 biomass level, the GC–MS total ion chromatograms of the bio-oils from the treated corn stover or aspen show only one major furfural peak accounting for about 80% of the area under the spectrum. We conclude that some catalysts improve bio-oil yields, and chloride salts in particular simplify the chemical compositions of the resultant bio-oils and therefore improve the product selectivity of the pyrolysis process.