, Techno-economic assessment of poly-3-hydroxybutyrate (PHB) production from methane-The case for thermophilic bioprocessing, Journal of Environmental Chemical Engineering http://dx.doi.org/10.1016/j.jece. 2016.07.033 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AbstractA major obstacle preventing the large scale production of polyhydroxyalkanoates (PHAs) has been the lack of a reliable, low cost, large volume feedstock. The abundance and relatively low price of methane therefore marks it as a substrate of interest. This paper presents a technoeconomic assessment of the production of poly-3-hydroxybutyrate (PHB) from methane.ASPEN Plus was used for process design and simulation. The design and economic evaluation is presented for production of 100,000 t/a PHB through methanotrophic fermentation and acetone-water solvent extraction. Production costs were estimated at $4.1-$6.8/kg PHA, which compares against a median price of $7.5/kg from other studies. Raw material costs are reduced from 30-50% of production for sugar feedstocks, to 22% of production for methane. A feature of the work is the revelation that heat removal from the two-stage bioreactor process contributes 28% of the operating cost. Thermophilic methanotrophs could allow the use of cooling water instead of refrigerant, reducing production costs to $3.2-5.4/kg PHA; it is noted that PHB producing thermophilic methanotrophs are yet to be isolated. Energy consumption for air compression and biomass drying were also identified as significant capital and operating costs and therefore optimisation of bioreactor height and pressure and biomass moisture content should be considered in future research.3
Solvothermal techniques allow the crystallization of high nuclearity products that are otherwise inaccessible by conventional techniques, directly from the reaction mixture. By this method, the reaction of the triangular species [Fe3O(OAc)6(H2O)3]Cl with benzotriazole (BtaH) produces an [Fe14] cluster (depicted) with a very large spin ground state.
Superheating alcohol solutions of simple trimetallic vanadium(III) precursors gives the octa- and decametallic vanadium(III) clusters [V(8)(OEt)(8)(OH)(4)(O(2)CPh)(12)] (1) and [V(10)(OMe)(20)(O(2)CMe)(10)] (2). Cluster 2 is the largest vanadium(III) cluster synthesised to date. Thus solvothermal synthetic techniques are an excellent route to high-nuclearity vanadium(III) clusters. Both 1 and 2 consist of a planar or near-planar array of V(III) ions. The metal ions in 1 are bridged by either a micro(2)-hydroxide and two micro(2)-benzoate groups or two micro(2)-ethoxides and a micro(2)-benzoate groups, the two bridging arrangements alternating around the ring. In 2 each pair of neighbouring metal ions is bridged by two micro(2)-methoxides and a micro(2)-acetate, and this molecule is the V(III) analogue of Lippard's famous "ferric wheel". Preliminary magnetic susceptibility studies show the exchange coupling in both complexes to be antiferromagnetic in nature, with the coupling stronger in 1 than in 2.
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