(517a) Process Simulation of Lignocellulosic Material Pyrolysis to Producing High Added-Value Chemicals

Sustainable processes and proper waste management have become increasingly priority for industries and governments. The current global scenario points out to the critical demand for renewable energy alternatives to drive the reduction of the market dependence with regards to the fossil fuels and their effects on climate change as a consequence of the greenhouse effect. In recent years, the biomass derivatives (such as corn, straw, bagasse, and many others) have become natural sources which the chemical composition is especially convenient for the production of fuels and chemicals. Biomass is a renewable resource derived from forestry, agriculture, agricultural crops, aquatic plants and food processing.

The biomass chemical and structural composition is highly dependent on the plant genetic factors, environmental influences and their chemical interactions. Derived-biomass materials have shown a high energy content. To converting the biomass into chemicals and fuels, fast pyrolysis technology has been found to be efficient because high heating rates favor the formation of liquid product.

The liquid phase derived from the biomass pyrolysis, conventionally termed bio-oil, is a complex mixture of organic compounds. The bio-oil is usually composed of aliphatic and aromatic hydrocarbons, organic acids, alcohols, esters, ethers, aldehydes, ketones and sugars.

Many of the chemical compounds found in the bio-oil are very useful for the chemical industry, including 5-hydroxymethylfurfural (HMF), 1,3-cyclopentadione, 2-methoxy-4-vinylphenol, levoglucosan, 4-hydroxy-3-methoxycinnamaldehyde and 2-methoxy-4-propylphenol. As an example, the 1,3-cycle-pentadione is found in widespread synthetic applications that include the synthesis of prostaglandins, antibiotics, herbicides, among other biologically active components. Its synthesis requires controlled and selective alkylation process. 2-methoxy-4-vinylphenol is an aromatic compound used as a flavoring agent, being one of the compounds responsible for the wheat natural aroma. The 4-hydroxy-3-methoxycinmaldehyde has antioxidant potential suitable for use in antioxidant and anti-radical research studies of ferulate activities. The 2-methoxy-4-propyl-phenol is applied to the enhancement of smoke, clove, spicy cinnamon and pepper, vanilla and fruit nuances.

Due to the complexity, experimental tests on biorefinery units tend to be expensive and time consuming. Process simulation is an effective way to study the pyrolysis process without the expenses and delays generated by laboratory-scaled tests. Studies on pyrolysis process modelling have scarcely provided full description of the biomass conversion kinetics. Most current studies have utilized kinetic parameters calculated based on experimentally obtained results of material conversion. Despite recent studies on integrated processes for chemical and energy use of biomass, a limited number of works has presented the pyrolysis process simulation, focusing on the high-added value products to replace non-renewable products. Based on this scenario, the present work presents a study on the thermal conversion of lignocellulosic residues through the fast pyrolysis process, from a biorefinery point-of-view, aiming to obtain HMF, levoglucosan and p-coniferaldehyde.

The simulation design was structured through elementary compositional simulation, using PRO/II® software. The process is based on the concept of biorefinery, coupling a fast pyrolysis unit to a separation process. The process was divided into three main stages: pre-treatment, pyrolysis and separation. The pyrolysis process modeling was developed based on the classic kinetic multi-stage model and the Diebold concept for the production of active cellulose. The result shows the viability of the production and recovery of HMF from an alternative source to petroleum derivatives.