Pressurised pyrolysis of Miscanthus using a fixed bed reactor

Area of Science:

• Biomass conversion and pyrolysis
• Materials science
• Chemical engineering

Background:

• Miscanthus x giganteus is a promising lignocellulosic biomass for energy applications.
• Pyrolysis offers a thermochemical route to convert biomass into valuable products like bio-oil and char.
• Understanding the influence of process parameters, such as pressure, is crucial for optimizing pyrolysis outcomes.

Purpose of the Study:

• To investigate the pyrolysis of Miscanthus x giganteus in a fixed-bed reactor.
• To analyze the composition of the resulting bio-oil and the properties of the char.
• To determine the effect of varying pressures on the pyrolysis products.

Main Methods:

• Pyrolysis of Miscanthus x giganteus in a fixed-bed reactor at a heating rate of 13°C/min to 550°C.
• Application of pressures ranging from atmospheric to 26 bar.
• Characterization of bio-oil components (water, phenols) and char properties (elemental analysis, surface area via BET, calorimetry, SEM, solid-state 13C NMR).

Main Results:

• Bio-oil primarily contained water, phenol, and phenol derivatives.
• Char produced was highly carbonized, particularly at elevated pressures.
• Char surface area was significantly affected by pressure, decreasing from 162 m²/g at atmospheric pressure to 0.137 m²/g at the highest pressure.
• Higher pressures yielded thermally stable char materials.

Conclusions:

• The pyrolysis of Miscanthus x giganteus yields bio-oil with potential platform chemical value and a highly carbonized char.
• Process pressure is a critical factor influencing char properties, especially surface area.
• The resulting char, particularly at higher pressures, exhibits thermal stability, suggesting potential for applications where high surface area is not required.