MgO-modified activated biochar for biojet fuels from pyrolysis of sawdust on a simple tandem micro-pyrolyzer

Design of experiments method into upgrading pyrolytic oil for sustainable aviation fuel additives by hydrotreating and hydrocracking

Recycling waste to produce liquid fuels for the automotive and aviation industries is a major global concern, especially in light of the ongoing energy crisis. Because waste is used in thermal conversion processes, the resulting liquid products often require additional processing to reduce their density and viscosity, and to remove oxygenated compounds or pollutants that hinder further utilization. Catalytic hydrogenolytic reactions such as hydrodeoxygenation (HDO) and hydrocracking (HC) have been extensively applied to upgrade pyrolysis oils. Selecting the appropriate catalyst and optimizing the process operating conditions are crucial for yielding high-quality fuel. Design of experiments (DOE) and analysis of variance (ANOVA) can identify the primary factors of the process and their possible interactions. This research focuses on the conversion of pyrolysis oil derived from car tires into jet fuel and aims to determine the optimal HDO and HC conditions to maximize the concentration of the kerosene fraction. Hydrodeoxygenation and hydrocracking reactions using NiMo/γ-Al2O3 catalysts are examined under varying temperature, pressure, and time conditions. The compositions of the raw tire pyrolysis oil (TPO) are mainly characterized by heteroatom content, aromatic compounds, olefins and acetylenes, alkanes, and cycloalkanes, which play key roles during HDO and HC procedures. Subsequently, the distillation and separation of the fuel fractions are carried out to determine the quality of the product.

A strategic recovery of value-added monomer from polycarbonate waste through catalytic pyrolysis on ultra-high porous MgO

The huge generation of plastic waste has become significant environmental problem. For environmentally sustainable plastic waste management, thermochemical recycling of widely used plastic waste such as polyethylene, polypropylene, polystyrene, and polyethylene terephthalate have vigorously studied. However, development of proper recycling process for other types of plastic waste is required. In this study, a thermo-catalytic treatment was applied for recovery of value-added monomers and gaseous products from polycarbonate (PC). The systematic study investigating the relationships between pyrolysis conditions (temperature, atmospheric gas, the presence of catalyst) and yield of value-added products was performed. To make the thermochemical process environmentally benign and more efficient, carbon dioxide (CO2) was used as an atmospheric gas in comparing to inert gas (N2). When CO2 was introduced, the yield of PC monomer, bisphenol A (BPA), was nearly doubled at 600 °C. At higher temperature, BPA yield decreased with the increased yield of gaseous products. Because CO2 was the major gaseous product, BPA recovery from the PC pyrolysis was the useful approach in PC disposal practice. To improve BPA yield from PC pyrolysis, two MgO catalysts were utilized (medium porosity MgO-1 and ultrahigh porosity MgO-2). Catalytic pyrolysis under CO2 environment increased BPA yield from 12.8 (pyrolysis without catalyst under N2) to 25.6 (MgO-1) and 30.5 wt% (MgO-2) at 600 °C. High porosity MgO catalyst was more effective in BPA production, and the catalyst deactivation was not shown for 4 consecutive reactions. This study informs that MgO catalyst and CO2 flow gas more than doubled the BPA yield from pyrolysis of PC in reference to conventional pyrolysis system (non-catalytic under N2).

Sodium hydroxide/magnesium chloride multistage activated sludge biochar: interfacial chemical behavior and Cd(II) adsorption performance

To enhance the adsorption performance of municipal sludge biochar on Cd(II), modified sludge biochar was prepared by sodium hydroxide/magnesium chloride (NaOH/MgCl2) graded activation, and the Cd(II) adsorption performance on sludge biochar (BC), NaOH-activated sludge biochar (NBC) and NaOH/MgCl2 activated sludge biochar (NBC-Mg) was investigated. The results showed that NaOH/MgCl2 graded activation upgraded the surface structure and enhanced the graphitization of sludge biochar. The adsorption experiments indicated that the adsorption kinetic and adsorption isotherm for Cd(II) were in accordance with the pseudo second-order kinetic and Langmuir model. The adsorption capacity of NBC-Mg (143.49 mg/g) for Cd(II) was higher than that of BC (50.40 mg/g) and NBC (85.20 mg/g). The mechanism of Cd(II) adsorption included ion exchange, complexation, cation-π interaction, and mineral precipitation. After five regeneration, the removal efficiency of Cd(II) by NBC-Mg remained above 90%. This work indicated that sludge biochar prepared by multistage activation could be an effective material for Cd-containing wastewater treatment.

Strategic use of crop residue biochars for removal of hazardous compounds in wastewater

Crop residues are affordable lignocellulosic waste in the world, and a large portion of the waste has been burned, releasing toxic pollutants into the environment. Since the crop residue is a carbon and ingredient rich material, it can be strategically used as a sorptive material for (in)organic pollutants in the wastewater after thermo-chemical valorization (i.e., biochar production). In this review, applications of crop residue biochars to adsorption of non-degradable synthetic dyes, antibiotics, herbicides, and inorganic heavy metals in wastewater were discussed. Properties (porosity, functional groups, heteroatom, and metal(oxide)s, etc.) and adsorption capacity relationships were comprehensively reviewed. The current challenges of crop residue biochars and guidelines for development of efficient adsorbents were also provided. In the last part, the future research directions for practical applications of the crop residue biochars in wastewater treatment plants have been suggested.

Pilot study on production of aviation fuel from catalytic conversion of corn stover

Aviation fuel is high energy density and is usually produced from refinery in petroleum industry. Production of renewable aviation fuel from biomass eases pressure of carbon emission regulation. The operational processes in this study include steam stripping, hydrolysis of residues, condensation reaction unit, autoclave hydrogenation, fixed-bed hydrodeoxygenation, and oil-upgrading unit. The biomass-derived aviation fuel has a low oxygen content of 0.4 %, while its high heat value is 45.5 MJ/kg. The aviation fuel ranges from C8 ∼ C15, and rich in isoparaffins (50.4 %) while the n-paraffins have a selectivity of 12.2 % and other components are cycloparaffins (19.0 %), aromatic hydrocarbons (11.3 %), and alkenes (5.6 %). The mass yield for aviation fuel from corn stover reaches 10.6 %. This pilot study achieved production of aviation fuel from raw biomass corn stover.

Recent advances in biowaste management towards sustainable environment

Bio-wastes and their utilization has been increasing enormously, due to its generation and management practices towards making the clearner environment. Bio-waste disposal that follow the emerging global human population has commended the hunt to certain methods sustainably for the bio-waste management to overwhelmed the ecological issues, prompted by means of the collection of such waste materials. The bio-conversion process of the various bio-wastes into high value added products seems to be practicable in various venues in terms of technological and financial supports. Thereby, this preface presentat about of bio-wastes management and new trends towards circular economy and challenges to acheive it by considering the Virtual Special Issue (VSI) dedicated in Bioresourse Technology Journal.

Assessment of the Catalytic Performances of Nanocomposites Materials Based on 13X Zeolite, Calcium Oxide and Metal Zinc Particles in the Residual Biomass Pyrolysis Process

Nanocomposites based on 13X zeolite (13XZ), calcium oxide (CaO) and metal zinc particles (Zn) were prepared. The resulting nanocomposites were characterized by different techniques. Then, a comparative study on catalytic and noncatalytic pyrolysis of biomass waste was performed to establish the influence of nanocomposites used as catalysts on the yields and characteristics of liquid and solid products. Residual rapeseed biomass (RRB) was employed for pyrolysis experiments and a fixed bed reactor was used. By introducing CaO and metal zinc particles into 13X zeolite mass, the surface area (S_BET) of nanocomposites was reduced, and this decrease is due to the introduction of nano-calcium carbonate and nano-zinc particles, which occupied an important space into zeolite structure. By adding CaO to 13XZ, the pore structure was changed and there was a decrease in the micropores volume. The analysis of the pore area distribution showed a hierarchical pore structure for nanocomposites. The elements composition showed that the main elements contained in nanocomposites are Si, Al, Ca and Zn, confirming the preservation of the zeolite structure. Using these nanocomposites as catalysts in pyrolysis process, the residual biomass could be valorized, producing bio-oil and biochar for the management and sustainability of this low-value waste.