Nourredine Abdoulmoumine

Positive and negative aspects of soda/anthraquinone pulping of hardwoods.

The positive aspects of the non-sulfur soda/anthraquinone (SAQ) process are mostly tied to improved energy efficiency while lower pulp brightness after bleaching is its most significant drawback. A credible method that quantifies bleachability as well as an approach that solves the problem for SAQ pulps from hardwoods will be described. A straight line correlation (R2=0.904) was obtained between O2 kappa number and final light absorption coefficient (LAC) value after standardized OD0EpD1 bleaching of nine hardwood kraft pulps from three laboratories and one pulp mill. The bleachability of pulps from four different soda processes catalyzed by anthraquinone (AQ) and 2-methylanthraquinone (MAQ) was compared to that of conventional kraft pulps by comparing O2 kappa number decrease and final LAC values. It was observed that a mild hot water pre-hydrolysis improved the bleachability of SAQ pulps to a level equal to that of kraft.

Structural changes in lignocellulosic biomass during activation with ionic liquids comprising 3-methylimidazolium cations and carboxylate anions

BackgroundLignocellulosic biomass requires either pretreatment and/or fractionation to recover its individual components for further use as intermediate building blocks for producing fuels, chemicals, and products. Numerous ionic liquids (ILs) have been investigated for biomass pretreatment or fractionation due to their ability to activate lignocellulosic biomass, thereby reducing biomass recalcitrance with minimal impact on its structural components. In this work, we studied and compared 1-allyl-3-methylimidazolium formate ([AMIM][HCOO]) to the commonly used 1-ethyl-3-methylimidazolium acetate ([EMIM][CH3COO]) for its potential to activate hybrid poplar biomass and enable high cellulose and hemicellulose enzymatic conversion. Although [EMIM][CH3COO] has been widely used for activation, [AMIM][HCOO] was recently identified to achieve higher biomass solubility, with an increase of 40% over [EMIM][CH3COO].ResultsSince IL activation is essentially an early stage of IL dissolution, we assessed the recalcitrance of [EMIM][CH3COO] and [AMIM][HCOO]-activated biomass through a suite of analytical tools. More specifically, Fourier transform infrared spectroscopy and X-ray diffraction showed that activation using [AMIM][HCOO] does not deacetylate hybrid poplar as readily as [EMIM][CH3COO] and preserves the crystallinity of the cellulose fraction, respectively. This was supported by scanning electron microscopy and enzymatic saccharification experiments in which [EMIM][CH3COO]-activated biomass yielded almost twice the cellulose and hemicellulose conversion as compared to [AMIM][HCOO]-activated biomass.ConclusionWe conclude that the IL [AMIM][HCOO] is better suited for biomass dissolution and direct product formation, whereas [EMIM][CH3COO] remains the better IL for biomass activation and fractionation.

Kinetics of the release of elemental precursors of syngas and syngas contaminants during devolatilization of switchgrass

In this study, the results from laboratory measurements of the devolatilization kinetics of switchgrass in a rapidly heated fixed bed reactor flushed with argon and operated at constant temperatures between 600 and 800°C was reported. Results indicate that switchgrass decomposes in two sequential stages during pyrolysis: stage I involves the evaporation and devolatilization of water and extractives and stage II involves that of hemicellulose, cellulose, and lignin. The estimated global activation energy for stage II increased from 52.80 to 59.39kJ/mol as the reactor temperature was increased from 600 to 800°C. The maximum conversion of carbon, hydrogen, oxygen, sulfur, and nitrogen ranged from 0.68 to 0.70, 0.90 to 0.95, 0.88 to 0.91, 0.70 to 0.80, and 0.55 to 0.66, respectively. The retention of alkali and alkaline earth metal (AAEM) species in the solid char after complete pyrolysis was significantly higher than in the original feed, indicating the importance of AAEM species in subsequent char processing.

Biomass gasification producer gas cleanup

Abstract In addition to primary gases, biomass-derived producer gas contains nonnegligible concentrations of undesirable byproducts collectively known as contaminants. Syngas contaminants are composed of tar-, nitrogen-, and sulfur-based compounds and halides and other trace metals that must be minimize their negative impacts on downstream processes or to adhere to environmental regulations. The producer gas cleanup consists of all processes that are employed to reduce the concentration of contaminants in raw producer gas prior to conditioning and utilization in downstream applications. This chapter discusses primary contaminants, the impact of operating conditions on them, their mitigation and regulations governing their emissions. Additionally, best of available technology (BAT) are discussed for select contaminants.

Kinetic Study of Palmitic Acid Esterification on Sulfated Zirconium Oxide

Biodiesel can be produced by homogeneous or heterogeneous catalysis. While homogeneous base catalysis has been traditionally used, heterogeneous acid catalysis is generating interest because of its potential superior promise of catalyzing both the conversion of free fatty acids and triglycerides into methyl esters. Solid acid catalysts such sulfated zirconium oxide have been investigated for their potential in biodiesel production due to their fast reaction rate and their ability to esterify cheaper but high free fatty acid content oil. In the present work, the kinetics of esterification of palmitic acid on sulfated zirconium oxide was studied in a batch reactor.