Advanced Thermochemical Conversion Approaches for Green Hydrogen Production from Crop Residues

The huge volumes of crop residues generated during the production,processing,and consumption of farm products constitute an ecological nuisance when ineffectively managed.The conversion of crop residues to green hydrogen is one of the sustainable management strategies for ubiquitous crop residues.Production of green hydrogen from crop residue sources will contribute to deepening access to clean and affordable energy,mitigating climate change,and ensuring environmental sustainability.However,the deployment of conventional thermochemical technologies for the conversion of crop residues to green hydrogen is costly,requires long residence time,produces low-quality products,and therefore needs to be upgraded.The current review examines the conventional,advanced,and integrated thermochemical conversion technologies for crop residues for green hydrogen production.After a brief overview of the conventional thermochemical techniques,the review delves into the broad narration of advanced thermochemical technologies including catalytic pyrolysis,microwave pyrolysis,co-pyrolysis,hyropyrolysis,and autothermal pyrolysis.The study advocates the deployment of integrated pyrolysis,anaerobic digestion,pyrolysis,and gasification technologies will ensure scalability,decomposition of recalcitrant feedstocks,and generation of high grade green hydrogen.The outlook provides suggestions for future research into cost-saving and sustainable integrated technologies for green hydrogen production towards achieving carbon neutrality and a circular bio-economy.

A sustainable thermochemical conversion of animal biomass to N-heterocycles

The production of high-valued organonitrogen chemicals,especially N-heterocycles,requires artificial N_(2)fixation accompanied by the consumption of fossil resources.To avoid the use of these energy-and resource-intensive processes,we develop a sustainable strategy to convert nitrogen-rich animal biomass into N-heterocycles through a thermochemical conversion process(TCP)under atmospheric pressure.A high percentage of N-heterocycles(87.51%)were obtained after the TCP of bovine skin due to the abundance of nitrogen-containing amino acids(e.g.,glycine,proline,and L-hydroxyproline).Animal biomass with more diverse amino acid composition(e.g.,muscles)yielded higher concentrations of amines/amides and nitriles after TCP.In addition,by introducing catalysts(KOH for pyrrole and Al_(2)O_(3)for cyclo-Gly-Pro)to TCP,the production quantities of pyrrole and cyclo-Gly-Pro increased to 30.79 mg g^(-1)and 38.88 mg g^(-1),respectively.This approach can be used to convert the significant animal biomass waste generated annually from animal culls into valued organonitrogen chemicals while circumventing NH3-dependent and petro-chemical-dependent synthesis routes.

Recent advances in thermochemical conversion of woody biomass for production of green hydrogen and CO_(2)capture:A review

Hydrogen as a clean energy carrier has attracted great interests world-wide for substitution of fossil fuels and for abatement of the climate change concerns.However,green hydrogen from renewable resources is less than 0.1%at present in the world hydrogen production and this is largely from water electrolysis which is beneficial only when renewable electricity is used.Hydrogen production from diverse renewable resources is desirable.This review presents recent advances in hydrogen production from woody biomass through biomass steam gasification,producer gas processing and H_(2)/CO_(2)separation.The producer gas processing includes steam-methane reforming(SMR)and water-gas shift(WGS)reactions to convert CH_(4)and CO in the producer gas to H_(2)and CO_(2).The H_(2)storage discussed using liquid carrier through hydrogenation is also discussed.The CO_(2)capture prior to the SMR is investigated to enhance H_(2)yield in the SMR and the WGS reactions.

Liquefaction of Kraft Lignin at Atmospheric Pressure

Kraft lignin was liquefied using polyethylene glycol#400(PEG)and glycerol(G)in a weight ratio of 80/20(w/w)and sulphuric acid(SA)as catalyst under atmospheric pressure at 160ºC.The three independent variables:reaction time(60,80 and 100 min),percentage of lignin(15,20 and 25%,w/w),and catalyst concentration(0,3 and 6%,w/w),were varied resulting in 27 experimental runs.The effect of these reaction conditions on the properties of the polyols was evaluated.The statistical analysis showed that only“the percentage of lignin”did not influence the properties of the liquefied products,however,reaction time and catalyst load were important parameters.The resulting liquefied products were characterized by FTIR analysis.

Thermochemical recycling of waste disposable facemasks in a non-electrically powered system

The COVID-19 pandemic encouraged the use of plastic-based personal protective equipment (PPE), which aidedgreatly in its management. However, the increased production and usage of these PPEs put a strain on the environment,especially in developing and underdeveloped countries. This has led various researchers to study low-costand effective technologies for the recycling of these materials. One such material is disposable facemasks. However,previous studies have only been able to engage electrically powered reactors for their thermochemical conversion,which is a challenge as these reactors cannot be used in regions with an insufficient supply of electricity. In thisstudy, the authors utilized a biomass-powered reactor for the conversion of waste disposable facemasks and almondleaves into hybrid biochar. The reactor, which is relatively cheap, simple to use, environmentally friendly, and modifiedfor biochar production, is biomass-powered. The co-carbonization process, which lasted 100 min, produced a 46%biochar yield, which is higher than previously obtained biochar yields by other researchers. The biochar thus obtainedwas characterized to determine its properties. FTIR analysis showed that the biochar contained functional groupssuch as alkenes, alkynes, hydroxyls, amines, and carbonyls. The EDX analysis revealed that the biochar was primarilymade of carbon, tellurium, oxygen, and calcium in the ratios of 57%, 19%, 9%, and 7%, respectively. The inclusion ofthe facemask decreased the surface area and porosity of the biochar material, as evidenced by its surface area andpore characteristics.

Size matters:small distributed biomass energy production systems for economic viability

Current large scale biomass energy production systems including cellulosic ethanol,gasification,and pyrolysis facilities face significant technical and economic hurdles.Compared with these large scale systems,small distributed biomass energy production systems(DBEPS)are believed to offer advantages including lower capital costs,lower feedstock costs,simplified transportation and logistics and higher returns for biomass producers.DBEPS compliant technologies are expected to make utilization of regional biomass supplies practical and economically viable in the near-term.This paper presents arguments on the need and importance of DBEPS,available DBEPS options,and an economic scenario of DBEPS implementation on an average size farm in the US.

Recent application of biochar on the catalytic biorefinery and environmental processes

Lignocellulosic biomass is an abundant and environment-friendly source for renewable energy production.The value and application of biochar,which is obtained from the thermochemical conversion of biomass,is increasing rapidly because of its high carbon content and porosity.The property of biochar,such as surface area,porosity,and number of functional groups,can be improved by controlling the conditions of biomass conversion,biochar activation,and functionalization methods.The production and activation of biochar as well as its potential use for soil remediation,pollutant adsorption,and biorefinery have been reviewed extensively over recent decades.This paper provides a conceptual approach for biochar production and activation together with its application as a catalyst for biorefineries and the removal of environmental contaminants.

Plastic crisis underscores need for alternative sustainable-renewable materials

The current global plastic crisis is triggered by several factors including increased costs of petrochemical feedstock and Covid-19 disruption of the transport sector(Yuan et al.,2021).This disruption of world-wide supply chains of polyethylene,polypropylene and other petroleum-based hydrocarbon chemicals has significantly increased shortage and prices of plastics in for example Europe over the last year,hence calling for sustainable alternatives to conventional plastics(WMW,2021,European Plastic Manufacturers sound the Alarm Bell on Supply Chain Disruption,Waste Management World.).This is critical due to extensive use of the non-biodegradable personal protective equipment(PPE)masks in the current pandemic,which might be even worse than the shortage of polyolefins at the moment(Deng et al.,2022).

Gasification kinetics of char formed from waste polyvinyl chloride for efficient utilization in ironmaking process

In the prevailing incineration processes of municipal solid waste,the presence of polyvinyl chloride(PVC)may cause environmental problems.The energy-intensive ironmaking sector in the iron and steel industry operates at high temperature and under high reduction potential with the function of energy conversion,which can provide a potential path for the collaborative utilization of waste plastics in large quantities and low cost.The gasification of the char formed from PVC when processed in the ironmaking sector is significant for the development of the related technologies.Thus,the gasification experiment of PVC char and traditional carbonaceous materials was performed by thermogravimetric analysis.The results indicated that the gasification ability decreased in the sequence of PVC char>anthracite coal>coke>graphite.Then,kinetics were also analyzed by Coats-Redfern and Doyle approximations.The PVC char showed the best gasification ability with the smallest activation energy,ranging from 87.18 to 117.52 kJ/mol,and the smaller graphitization degree of PVC char compared with other carbonaceous materials should be the main reason for its excellent gasification reactivity.

Influence of Ca(OH)_(2) on ash melting behaviour of woody biomass

Woody biomass is a renewable source offering high potential for production of bio-fuels,-chemicals and-energy.During the outdoor storage of biomass biodegradation processes take place,which leads to mass reduction up to 30 wt%.To avoid these mass losses,the biomass was mixed with Ca(OH)_(2) in different ratios.To ensure,that this additive does not negatively influence further thermo-chemical conversion of biomass(e.g.by fluidized bed combustion),the spruce and poplar ash with and without additive was tested using ash melting microscopy.It was demonstrated that all the characteristic temperatures(DT,HT,FT)were significantly higher than the thermo-chemical conversion process temperatures in a fluidized bed.Thus it could be pointed out that the addition of Ca(OH)_(2) does not negatively influence ash melting behaviour,ash melting temperature respectively.