Direct Production of Propene from the Thermolysis of Poly(β-hydroxybutyrate) (PHB). An Experimental and DFT Investigation

Optimisation of Propane Production from Hydrothermal Decarboxylation of Butyric Acid Using Pt/C Catalyst: Influence of Gaseous Reaction Atmospheres

The displacement and eventual replacement of fossil-derived fuel gases with biomass-derived alternatives can help the energy sector to achieve net zero by 2050. Decarboxylation of butyric acid, which can be obtained from biomass, can produce high yields of propane, a component of liquefied petroleum gases. The use of different gaseous reaction atmospheres of nitrogen, hydrogen, and compressed air during the catalytic hydrothermal conversion of butyric acid to propane have been investigated in a batch reactor within a temperature range of 200–350 °C. The experimental results were statistically evaluated to find the optimum conditions to produce propane via decarboxylation while minimizing other potential side reactions. The results revealed that nitrogen gas was the most appropriate atmosphere to control propane production under the test conditions between 250 °C and 300 °C, during which the highest hydrocarbon selectivity for propane of up to 97% was achieved. Below this temperature range, butyric acid conversion remained low under the three reaction atmospheres. Above 300 °C, competing reactions became more significant. Under compressed air atmosphere, oxidation to CO2 became dominant, and under nitrogen, thermal cracking of propane became significant, producing both ethane and methane as side products. Interestingly, under a hydrogen atmosphere, hydrogenolytic cracking propane became dominant, leading to multiple C–C bond cleavages to produce methane as the main side product at 350 °C.

Vapor-phase conversion of aqueous 3-hydroxybutyric acid and crotonic acid to propylene over solid acid catalysts

Vapor phase conversion of 3-hydroxybutyric and crotonic acid to propylene in a continuous-flow reactor over silica–alumina and niobium catalysts demonstrates a new strategy for producing renewable fuels and chemicals from wastewater carbon.

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

Medium chain-length linear α-olefins (mcl-LAO) are versatile precursors to commodity products such as synthetic lubricants and biodegradable detergents, and have been traditionally produced from ethylene oligomerization and Fischer–Tropsch synthesis. Medium chain-length polyhydroxyalkanoic acid (mcl-PHA) can be produced by some microorganisms as an energy storage. In this study, Pseudomonas putida biomass that contained mcl-PHA was used in HTL at 300 °C for 30 min, and up to 65 mol% of mcl-PHA was converted into mcl-LAO. The yield and quality of the bio-oil co-produced in the HTL was remarkably improved with the biomass rich in mcl-PHA. Experiments with extracted mcl-PHA revealed the degradation mechanism of mcl-PHA in HTL. Overall, this work demonstrates a novel process to co-produce mcl-LAO and bio-oil from renewable biomass.

Co-production of fully renewable medium chain α-olefins and bio-oil by hydrothermal liquefaction.