Pyrolysis of Waste Biomass – Technical and Process Achievements, and Future Development – A Review

The slow pyrolysis characteristics of lignocellulosic biomass and its three major components via a Thermogravimetric Analyzer coupled with a Fourier Transform Infrared Spectrometer (TGA-FTIR) was studied. Different compositions and ratios of cellulose, hemicellulose, and lignin, olive pomace, sunflower waste, and pinecone were selected. The main decomposition temperature ranges of xylose (hemicellulose) and lignin showed a broad range between 173–690 and 170–835 °C, respectively, whereas that of cellulose was detected to be 291–395 °C. All biomass samples presented a three-stage pyrolysis model that is explained by the superposition of the weight losses of major components. Simultaneous FTIR analysis of the evolved gases demonstrated that the greater the cellulose and hemicellulose contents, the higher the CO and CO2 concentrations. Chemical kinetics were computed with the Coats–Redfern model. The activation energy required for the initiation of the thermal decomposition of biomass samples is in the range of 53–94 kJ/mol. Moreover, the product yields of all samples were determined via laboratory-scale pyrolysis. Pyrolytic oil and char yields were determined to be between 18.9–32.4 wt.% and 26.6–31.2 wt.%, respectively, at 550 °C final temperature for the biomass samples. It is concluded that the bio-oil yield was not only controlled by the cellulose content but also affected by the presence of n-hexane soluble (oil) fraction as well as inorganics.

TGA-FTIR Analysis of Biomass Samples Based on the Thermal Decomposition Behavior of Hemicellulose, Cellulose, and Lignin

Apaydın-Varol

Mutlu

2023

Solid Biofuel Production from Biomass: Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

Obi,

Olugbade,

Orisaleye

et al. 2023

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria.

Polyolefin Pyrolysis in Multilayer Fluidized Beds: An Innovative Approach to Obtain Valuable Alternative Fuels

Żukowski,

Leski,

Berkowicz-Płatek

et al. 2024

This paper presents the application of two versions of the multilayer fluidized bed made out of two materials with significantly different densities. The first type of fluidized bed was composed of raw cenospheres and quartz sand. The second type of fluidized bed was composed of cenospheres coated with iron oxides and quartz sand. A variable vertical density profiles in the prepared fluidized beds were confirmed, making them suitable for processing polymeric materials, specifically, polyolefins with a density below 1 g/cm3. The polyolefin pyrolysis process was investigated in both versions of the fluidized bed at temperatures of 520, 540, 560, and 590 °C. The products of the pyrolysis were monitored using high-resolution infrared spectroscopy (with a resolution of 1 cm−1). While the process is organized in these fluidized beds, the absence of the accumulation of solid residues is notable. The results show that the pyrolytic gaseous mixture is composed of numerous compounds, namely, unsaturated and saturated aliphatic hydrocarbons and benzene. The possibility of producing a gas rich in ethylene, propylene, and 1-butene during the pyrolysis was demonstrated. Additionally, during the pyrolysis of both polymers, the production of benzene was shown with yields, ranging from 5%wt. in the fluidized bed made out of raw cenospheres to 11 %wt. in the fluidized bed made out of cenospheres modified by iron oxides. Due to the complex nature of the resulting pyrolytic gas, it is suggested that we process the created gaseous mixtures entirely in a steam conversion process, making them a potential source of hydrogen.