Catalytic fast pyrolysis of lignocellulosic biomass

Abstract

Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel-bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating value, high corrosiveness, high viscosity, and instability; they also greatly limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

Quantitative Insights into the Fast Pyrolysis of Extracted Cellulose, Hemicelluloses, and Lignin

“…However, a number of concerns with regard to the quality of fast pyrolysis bio‐oil have been raised (i.e., instability, high variability in chemical composition, high water content, immiscibility with petroleum‐derived fuels, changing viscosity, phase separation) that prevent its upgrading for commercial applications 3. In particular, the high level of oxygen in fast pyrolysis oils requires the application of intensive post‐treatments to deoxygenate these liquids selectively, which has resulted in intense scientific activity in the field of catalytic fast pyrolysis4 and bio‐oil upgrading in the last decade 5. A considerable number of catalysts has been developed as a result of the chemical diversity of the components in bio‐oils 4.…”

“…In particular, the high level of oxygen in fast pyrolysis oils requires the application of intensive post‐treatments to deoxygenate these liquids selectively, which has resulted in intense scientific activity in the field of catalytic fast pyrolysis4 and bio‐oil upgrading in the last decade 5. A considerable number of catalysts has been developed as a result of the chemical diversity of the components in bio‐oils 4. Whatever the processing approach (i.e., ex situ or in situ) or catalysis approach (i.e., homogeneous or heterogeneous) used, it is reasonable to think that a better understanding of the origin of the constituent chemicals in bio‐oil could have a beneficial impact on the overall performance of these processes.…”

Characterization of Thermo-Chemical Degradation and Pyrolysis Properties for Three Kinds of Biomass Residues

“…Meanwhile, the HHV of all three samples was higher than rice straw and corn stalk, especially PSS, which was the highest at 23.88 MJ/kg. The high HHV values may have caused an increase in the calorific value and improvement in the quality of bio-oil during pyrolysis (Lou and Wu 2011;Liu et al 2014). (Ferdinand et al 2012) …”

On-line Analysis of Catalytic Reaction Products Using a High-Pressure Tandem Micro-reactor GC/MS

“…14,15 The CFP of biomass has been studied under various reaction conditions with different temperatures and pressures. [1][2][3][4][5][6] Liquid fuels, i.e. bio-oils, produced from the fast pyrolysis of lignocellulosic biomass, have a high content of water and oxygen, which cause some undesirable properties, such as poor chemical and thermal stabilities.…”

“…[1][2][3][4] The depolymerized species, i.e. pyrolyzates, can be catalytically converted to gaseous and liquid products that are further upgraded to fuels and value-added chemicals.…”