Succinic acid, derived from fermentation of agricultural carbohydrates, has a specialty chemical market in industries producing food and pharmaceutical products, surfactants and detergents, green solvents and biodegradable plastics, and ingredients to stimulate animal and plant growth As a carbon-intermediate chemical, fermentation-derived succinate has the potential to supply over 27 × 108 kg industrial products/year including: 1,4-butanediol, tetrahydrofuran, γ-butyrolactone, adipic acid, n-methylpyrrolidone and linear aliphatic esters Succinate yields as high as 110 g/l have been achieved from glucose by the newly discovered rumen organism Actinobacillus succinogenes Succinate fermentation is a novel process because the greenhouse gas CO2 is fixed into succinate during glucose fermentation New developments in end-product recovery technology, including water-splitting electrodialysis and liquid/liquid extraction have lowered the cost of succinic acid production to US $ 055/kg at the 75 000 tonne/year level and to $ 220/kg at the 5000 tonne/year level Research directions aimed at further improving the succinate fermentation economics are discussed

Biotechnology of succinic acid production and markets for derived industrial products

The last 15 years of hydroformylation and carbonylation chemistry are reviewed, including technical and commercial aspects.

Progress in hydroformylation and carbonylation

Bio-based succinate is receiving increasing attention as a potential intermediary feedstock for replacing a large petrochemical-based bulk chemical market. The prospective economical and environmental benefits of a bio-based succinate industry have motivated research and development of succinate-producing organisms. Bio-based succinate is still faced with the challenge of becoming cost competitive against petrochemical-based alternatives. High succinate concentrations must be produced at high rates, with little or no by-products to most efficiently use substrates and to simplify purification procedures. Herein are described the current prospects for a bio-based succinate industry, with emphasis on specific bacteria that show the greatest promise for industrial succinate production. The succinate-producing characteristics and the metabolic pathway used by each bacterial species are described, and the advantages and disadvantages of each bacterial system are discussed.

Prospects for a bio-based succinate industry

The valorisation of the plant biopolymer lignin is now recognised as essential to enabling the economic viability of the lignocellulosic biorefining industry. In this context, the “lignin-first” biorefining approach, in which lignin valorisation is considered in the design phase, has demonstrated the fullest utilisation of lignocellulose. We define lignin-first methods as active stabilisation approaches that solubilise lignin from native lignocellulosic biomass while avoiding condensation reactions that lead to more recalcitrant lignin polymers. This active stabilisation can be accomplished by solvolysis and catalytic conversion of reactive intermediates to stable products or by protection-group chemistry of lignin oligomers or reactive monomers. Across the growing body of literature in this field, there are disparate approaches to report and analyse the results from lignin-first approaches, thus making quantitative comparisons between studies challenging. To that end, we present herein a set of guidelines for analysing critical data from lignin-first approaches, including feedstock analysis and process parameters, with the ambition of uniting the lignin-first research community around a common set of reportable metrics. These guidelines comprise standards and best practices or minimum requirements for feedstock analysis, stressing reporting of the fractionation efficiency, product yields, solvent mass balances, catalyst efficiency, and the requirements for additional reagents such as reducing, oxidising, or capping agents. Our goal is to establish best practices for the research community at large primarily to enable direct comparisons between studies from different laboratories. The use of these guidelines will be helpful for the newcomers to this field and pivotal for further progress in this exciting research area.

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Guidelines for performing lignin-first biorefining

Deactivation in Homogeneous Transition Metal Catalysis: Causes, Avoidance, and Cure

Gas-liquid volumetric mass transfer coefficients, (kLa), have been obtained for “dead-end” autoclave reactors operated in two different modes: (a) gas introduced into the gas phase, and (b) gas introduced through a dip-tube in the liquid. Three different methods of kLa determination have been compared. Effects of agitation speed, impeller diameter, gas to liquid volume ratio (Vg/VL), position of the impeller and reactor size on kLa have been investigated. The kLa data were found to be correlated as:



kLa = 1.48 × 10−3 (N)2.18 (Vg/VL)1.88 (dI/dT)2.16 (h1/h2)1.16



The critical speed of surface breakage, at which transition from the surface convection to the surface entrainment regime occurs, was also determined for different impeller positions, impeller diameters and gas to liquid volume ratios.



On a obtenu des coefficients volumiques de transfert de matiere gaz-liquide (kLa) pour des reacteurs de type autoclave sans circulation fonctionnant sous deux modes differents: (a) gaz introduit dans la phase gazeuse; (b) gaz introduit dans le liquide au moyen d'un tube immerge. On a compare trois methodes de determination de kLa. On a etudie l'effet de la vitesse d'agitation, du diametre de la turbine, du rapport volume de gaz sur volume de liquide (Vg/VL), de la position de la turbine ainsi que de la taille du reacteur sur le coefficient kLa. Les donnees ont ete correlees de la maniere suivante:



kLa = 1,48 × 10-3(N)2.18 (Vg/VL)1.18 (dI/dT)2.16 (h1/h2)1.16



La vitesse critique de rupture de la surface correspondant a une transition entre un regime convectif de surface et un regime d'entraǐnement de surface, a egalement ete determines pour differentes positions et diametres de turbine et differents rapports volume de gaz sur volume de liquide.

Gas-liquid mass transfer in "dead-end"autoclave reactors

Deactivation of homogeneous HRh(CO)(PPh3)3 catalyst in hydroformylation of 1-hexene

The kinetics of hydroformylation of propylene using an unmodified cobalt carbonyl catalyst has been investigated in a temperature range of 383-423K and a pressure range of 35-100 bar. Effects of the propylene and catalyst concentrations and the partial pressures of carbon monoxide and hydrogen on the rate of hydroformylation have been measured. Initial rates were found to be in the kinetic regime for the intensively stirred reactor used. An empirical rate model has been proposed, which was found to represent the rate data with a standard deviation of 7%. Its two kinetic parameters were evaluated, and the activation energy was found to be 77 kJ/mol

Hydroformylation of propylene using an unmodified cobalt carbonyl catalyst: a kinetic study

Selectivity in hydroformylation of 1-decene by homogeneous catalysis☆

Isomer distribution and kinetics of the formation of n-butyraldehyde and isobutyraldehyde have been determined for the hydroformylation of propylene using unmodified cobalt carbonyl catalyst. Effects of the propylene and catalyst concentrations and the partial pressures of carbon monoxide and hydrogen on the n/iso ratio as well as on the individual reaction rates have been measured in a temperature range of 383-423K and a pressure range of 35-100 bar. An empirical rate model describing the intrinsic kinetics for each butyraldehyde has been proposed and its kinetic parameters evaluated. Such information is useful for the preferential production of n-butyraldehyde

R.V. Gholap

Papers

Gas-liquid mass transfer in "dead-end"autoclave reactors

Deactivation of homogeneous HRh(CO)(PPh3)3 catalyst in hydroformylation of 1-hexene

Hydroformylation of propylene using an unmodified cobalt carbonyl catalyst: a kinetic study

Selectivity in hydroformylation of 1-decene by homogeneous catalysis☆

Hydroformylation of propylene using unmodified cobalt carbonyl catalyst: selectivity studies