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This work presents a numerical investigation into CO2 valorization via the gasification of poplar wood. It is aimed at determining an optimum gasification condition for enhancing the production of syngas with a flexible H2 to CO molar ratio (H2/CO), which is essential in many petrochemical processes. The research is performed by simulation in ASPEN Plus, where steam and CO2 are fed as co-gasifying agents. The equilibrium concentrations of the product gas are obtained, and the H2/CO as well as the heating value of the resulting syngas are quantified. It is found that the inclusion of CO2 as a co-gasifying agent promotes CO evolution through the Boudouard reaction. However, it reduces H2 concentration, and consequently decreases the H2/CO. Furthermore, the effects of some process parameters have been studied in this work. It is observed that H2/CO reduces with a rise in temperature, increases with increasing CO2 to biomass ratio (CBR), and shows no significant change with pressure. Results further show that methanol synthesis from syngas can be achieved at temperatures close to 660 °C, while oxo-synthesis requires a higher temperature. A CBR of around 0.6 in the present work would be an optimum value for Fischer-Tropsch synthesis to achieve a H2/CO of 2:1, but the CBR should be lower for processes requiring a lower H2/CO like acetic acid formation and oxo-synthesis.

Synthesis gas production is a technology that dates to the 1950s. Recently, the conversion of hydrocarbons to syngas has played an important role in various applications from gas-to-liquid (GTL) processes to fuel cell applications. However, the current industrial production method is only profitable when large quantities of syngas are produced and generates high amounts of CO2 as a by-product. With the growing demands for smaller-scale and mobile syngas production technology, the catalytic partial oxidation of hydrocarbons has become a promising alternative to the conventional methane steam reforming technology. With the infrastructure for production and distribution of many commercial fuels already in place, numerous studies have been done on conversion of these fuels into syngas. This paper reviews the research that has been done in the past decade on the catalytic partial oxidation of conventional fuels and biofuels. The challenges faced in catalyst development are described as well as solutions that have been proposed to address those challenges. Advances in kinetic modelling of catalytic partial oxidation are presented, and techniques used to develop such models have also been highlighted. Finally, research gaps have been identified and recommendations have been given for further investigations to address current challenges.

Preparation of feedstock is a major energy intensive process for the thermochemical conversion of biomass into fuel. By eliminating the need to grind biomass prior to the torrefaction process, there would be a potential gain in the energy requirements as the entire step would be eliminated. In regards to a commercialization of torrefaction technology, this study has examined heat transfer inside large cylindrical biomass both numerically and experimentally during torrefaction. A numerical axis-symmetrical 2-D model for heat transfer during torrefaction at 270°C for 1 h was created in COMSOL Multiphysics 5.1 considering heat generation evaluated from the experiment. The model analyzed the temperature distribution within the core and on the surface of biomass during torrefaction for various sizes. The model results showed similarities with experimental results. The effect of L/D ratio on temperature distribution within biomass was observed by varying length and diameter and compared with experiments in literature to find out an optimal range of cylindrical biomass size suitable for torrefaction. The research demonstrated that a cylindrical biomass sample of 50 mm length with L/D ratio of 2 can be torrefied with a core-surface temperature difference of less than 30 °C. The research also demonstrated that sample length has a negligible effect on core-surface temperature difference during torrefaction when the diameter is fixed at 25 mm. This information will help to design a torrefaction processing system and develop a value chain for biomass supply without using an energy-intensive grinding process.

Black liquor (spent cooking liquor) is one of the major byproducts of pulp and paper manufacturing. Black liquor contains 10–50% lignin, which is the main organic matter found within that liquor. Different types of black liquors are obtained as per the type of feedstock, pulping process and cooking method adopted by industries. In recent years, industries have been required to accommodate newer varieties of feedstock such as non-wood and recycled fibers during the delignification process, which can save plenty of trees and hence reduce their carbon footprint. Therefore, the newer black liquors being generated differ in their physical characteristics, chemical composition, and energy content from that of traditional processes.Currently, black liquor is seen as a platform for the production of many renewable materials for industrial applications that can be environmentally friendly with the potential to be used substitute for fuel and commercial materials. However, most of the published review articles focus on the kraft spent liquor and its derived kraft lignin that is obtained from kraft pulping process at the pulp and paper as a source of bio-fuel and biomaterials. Meanwhile, several other black liquors such as soda, and neutral sulfite spent (NSSC) liquor and their derived lignin are not highlighted as sources of biofuel and biomaterials. Therefore, this review highlights all the types of black liquors including soda, and neutral sulfite spent (NSSC) liquor in terms of their sources, physical and chemical characterization, purification processes, and the potential applications of black liquor and its derived lignin.

Biomass pyrolysis has played an important role in environmental management by providing fuel and value-added chemicals from renewable resources. However, the variability in the properties of biomass necessitates the need for tunable catalysts that can favor specific reactions to target desirable compounds. Acid sites on catalysts are required for the cleavage of C C and C O bonds. While zeolite has been the most historically used catalyst for these processes, other materials such as silica and biomass-derived activated carbon have garnered the interest of researchers. All three types of catalysts have their strengths and weaknesses. In this study, the authors detail the synthesis and application of these catalysts in pyrolysis reactions. Advancements made in recent years were explored in detail, and key factors that influence the activity and stability of each type of catalysts are highlighted. The authors also provide their perspective on all three materials in terms of their potential to provide potential advancements in the field of catalytic pyrolysis. Finally, future research directions are indicated and summarized, based on results published in the literature with a particular focus on the development of composite to overcome the major challenges posed by the conventional catalysts.

The present research work is an attempt to focus on thermal kinetics of raw and torrefied hybrid poplar wood (Populus nigra – NM6). The results of the experiment under the optimal condition based o...

This chapter presents plastic waste treatment by chemical recycling techniques that convert plastic waste into fuel and other valuable products. The status, challenges, competitive technologies, and opportunities for further research in plastic waste gasification are explored in the chapter. Pyrolysis and plasma gasification are identified as the competitive technologies to gasification. The chapter also discusses different types of reactor for plastic waste gasification and pyrolysis, and operating conditions affecting their performances in laboratory, pilot, and industrial scales. The operating parameters that are common to the discussed chemical plastic recycling processes are temperature, pressure, type of feedstock, and catalysts. Currently, there are several reactor types available for conversion of plastics. However, the commercialization of the thermo-chemical conversion processes is still in progress and much investigation is required to design more robust systems. The use of heterogeneous catalysts in pyrolysis is a promising technique because they can be optimized to increase the yield of desired products and at lower temperatures. Catalysts are also used in copyrolysis of plastic wastes and biomass to produce certain desired products. Product distribution in terms of gas, char, tar, and oil from various investigators is presented in this chapter. Another interesting aspect covered in the chapter is cogasification of plastic waste with biomass and/or coal.

The application of black (spent) liquors for bio-carbon production is a promising method to add value to this industrial renewable waste stream. Further valorization by conversion to higher grade bio-carbon products may significantly enhance their adoption to various industrial uses. To increase the purity of the bio-carbon by selective removal of minerals and ash, a novel oxidative procedure performed at room temperature was developed and its potential was evaluated. The procedure was carried out with hydrogen peroxide (H2O2) as oxidant on three different types of spent liquor, namely neutral sulphite semi-chemical spent liquor (NSSCSL) sourced from recycled paper, softwood (pine and spruce) kraft spent liquor (PSKSL), and hardwood (aspen and balsam poplar) kraft spent liquor (APKSL). The efficiency of the oxidation procedure on each raw material was studied and reported. The maximum mass yield of bio-carbon was 31.88%, 46.27% and 43.93% after the ash removal processing of NSSCSL, PSKSL, and APKSL spent liquors respectively. The maximum efficiency for mineral and ash removal from spent liquors achieved were 94.63%, 98.08 %, and 94.93% respectively for the three types of spent liquors. The highest heating values (HHV) demonstrated in the bio-carbon produced were 26.11 MJ/kg, 24.74 MJ/kg, and 26.89 MJ/kg respectively. Empirical indices were also calculated to establish and characterize bio-carbons potential for its combustion quality as a function of this oxidation process. The upgraded bio-carbon appears to enhance their potential as environment friendly, green substitutes for solid fuel and bio-material applications.

Hydrothermal carbonization (HTC) is a useful method to convert wet biomass to value-added products. Fruit waste generated in juice industries is a huge source of moist feedstock for such conversion to produce hydrochar. This paper deals with four types of fruit wastes as feedstocks for HTC; namely, rotten apple (RA), apple chip pomace (ACP), apple juice pomace (AJP), and grape pomace (GP). The operating conditions for HTC processing were 190 °C, 225 °C, and 260 °C for 15 min. For all samples, higher heating value and fixed carbon increased, while volatile matter and oxygen content decreased after HTC. Except for ACP, the ash content of all samples increased after 225 °C. For RA, AJP, and GP, the possible explanation for increased ash content above 225 °C is that the hydrochar increases in porosity after 230 °C. It was observed that an increase in HTC temperature resulted in an increase in the mass yield for RA and GP, which is in contrast with increasing HTC temperature for lignocellulose biomass. Other characterization tests like thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) also showed that the HTC process can be successfully used to convert fruit wastes into valuable products.