A critical review of the production and advanced utilization of biochar via selective pyrolysis of lignocellulosic biomass.

The increasing demand for energy and diminishing sources of fossil fuels have called for the discovery of new energy sources. The effective energy conversion process of biomass is able to fulfill energy needs. Among the advanced biomass conversion technologies, thermochemical processes hold considerable potential approaches and needed for optimization. Thus, this study presents a comprehensive review of the research and development on the effects of catalysts on the thermochemical conversion of biomass to determine the progress of catalytic thermochemical conversion processes. The effects of catalysts on torrefaction, pyrolysis, hydrothermal liquefaction, and gasification are highlighted. Aspects related to reaction conditions, reactor types, and products are discussed comprehensively with the reaction mechanisms involved in the catalytic effects. Hydrogenation and hydrodeoxygenation can occur in the presence of zeolite catalysts during fast pyrolysis while producing highly aromatic bio-oil. A heterogeneous catalyst in liquefaction increases the hydrocarbon content and decreases viscosity, acid value, and oxygenated compounds in the bio-oil. Thus, expanding and enhancing knowledge about catalyst utilization in the thermochemical conversion technologies of biomass will play an important role in the generation of renewable and carbon-neutral fuels.

Catalytic thermochemical conversion of biomass for biofuel production: A comprehensive review

At present, renewable and biodegradable biocomposites materials have drawn much attention as promising green materials in different domains of application such as intelligent food packaging, biomedical and drug delivery, bio-membranes, automotive, as well as in industrial composting applications. The current review deals with the advances in preparation methods and technical applications of these biocomposites. Different biomass materials obtained from renewable resources such as coffee grounds (CG), nanocellulose and date stones are developed to be used as smart reinforcing agents in biodegradable biopolymers for improving their overall properties. Conversely, some drawbacks are associated with the use of lignocellulosic materials as reinforcing agents, especially their high humidity absorption, poor wettability, and incompatibility with most biopolymers. Thus, novel processing techniques and different aspects are proposed in this review to produce high performance lignocellulosic reinforced materials with better properties. Facial and green modification of organoclay (OC) by antibacterial natural rosin and stearic acid to obtain toxicity-free expanded OC is also discussed. Green modification using OC can also be used as compatibilizing and reinforcing material for different incompatible biopolymers such as chitosan, carboxy methyl cellulose (CMC) and polylactic acid (PLA). Ultimately, the future vision on the challenges and the environmental issues towards CO2 emission which is associated to the risk assessment of these bionanomaterials are also discussed.

Eco-friendly polymer composites for green packaging: Future vision and challenges

Biomass accounts for the largest renewable energy in the world, whereas its inherent drawbacks, such as low energy and mass density, hydrophilicity, poor grindability and severe ash-related issues, inhibit its extensive utilization. Torrefaction, conducted at 200–300 °C in an inert atmosphere, successfully overcomes the abovementioned drawbacks and improves the biomass applications. Thus, a critical review is performed for the new insight into further study, involving the properties improvement of torrefied biomass, applications on combustion and gasification, as well as the intractable challenges of ash-related issues during thermal conversion and economy viability. Compared to torrefaction duration and the moisture and size of biomass, the torrefaction temperature has the strongest impact on the biomass properties improvement. Respecting physical properties (energy density and grindabilty) and chemical thermal conversion characteristics, there exists an optimal torrefaction temperature at approximate 250 °C. Biomass torrefaction is strongly dependent on the degradation of hemicellulose. Herbaceous residues possess a higher degradation ratio compared to ligneous biomass; Besides, deciduous trees mainly containing xylan in hemicellulose are more active than coniferous trees which mainly contain glucomannan in hemicellulose. The torrefied biomass possesses increased carbon content, decreased H/C and O/C ratios, increased mass energy density, similar chemical compositions with coal, and the availability for gasification and co-firing. Moreover, large amount of Cl, S, and K release during torrefaction, which bring considerable fringe benefits by reduction or elimination of the intractable ash-related issues during thermal conversion, such as slagging, agglomeration and corrosion. At present, the cost of biomass torrefaction is higher than coal. However, it can be significantly reduced by the implementation of carbon credits market, increasing torrefaction plant equipment size, and empirical cumulation. Later, more attention should be focused on application demonstration and systematic economic optimization.

Biomass torrefaction: properties, applications, challenges, and economy

The global dependence on fossil reserves as well as the environmental aspects related to them are some of the factors that propel research on renewable energy forms Gasification, a thermochemical process that converts carbonaceous resources into syngas, is an advantageous alternative due to its relatively low costs, high efficiencies, and syngas’ wide variety of applications Although gasification is a very promising heat, power, and fuel production technique, there is still a field of improvement in gasification in fluidized beds when it comes to operation under high pressure and with feedstocks containing moderate or high moisture contents Thus, to provide enough information to address such questions, the present work aims at bringing an overview of gasification concepts, as well as an in-depth discussion based on simulation, laboratory- and demonstration-scale works of the effects of biomass water content and pressure on different parameters of several fluidized bed gasifiers Moreover, diverse strategies for handling high-moisture content biomass materials are presented, as well as the achievements and technical difficulties encountered by worldwide development and demonstration plant projects that designed and used pressurized fluidized-bed gasifiers

Handing Chen

Papers

Release and transformation characteristics of K and Cl during straw torrefaction and mild pyrolysis

Effect of torrefaction on the properties of rice straw high temperature pyrolysis char: Pore structure, aromaticity and gasification activity

Study on reactivity characteristics and synergy behaviours of rice straw and bituminous coal co-gasification.

Release and transformation behavior of Cl during pyrolysis of torrefied rice straw

Gravity discharge characteristics of biomass-coal blends in a hopper