Reaction decoupling in thermochemical fuel conversion and technical progress based on decoupling using fluidized bed

Thermochemical conversion of fuels via pyrolysis/carbonization,cracking,gasification and combustion has to involve a number of individual reactions called attribution reactions to form an intercorrelated reaction network for any conversion process.By separating one or some attribution reactions from the others to decouple their interactions existing in the reaction network,the so-called reaction decoupling enables a better understanding of the complex thermal conversion process and further the optimization of the conditions for attribution reactions as well as the entire conversion process to realize advanced performances.The dual bed conversion and two-stage conversion are the two representative types of fuel conversion technologies developed in recent years based on reaction decoupling.Many technical advantages have been proven for such decoupling fuel conversion technologies,such as poly-generation of products,low-cost production of high-grade products,elimination of undesirable products or pollutants,easy operation and control,and so on.The treated fuels with decoupling conversion technologies mainly include solid biomass and coal,as well as liquid petroleum oil.This paper is devoted to reiteration of the reaction decoupling concept and further to reviewing the research,developments and successful applications of several decoupling fuel conversion technologies of two such types by using fluidized bed as their major reactors.

Microbial-driven ectopic uranium extraction with net electrical energy production

The extraction of uranium (U) from U-bearing wastewater is of paramount importance for mitigating negative environmental impacts and recovering U resources. Microbial reduction of soluble hexavalent uranium (U(VI)) to insoluble tetravalent uranium (U(IV)) holds immense potential for this purpose, but its practical application has been impeded by the challenges associated with managing U-bacterial mixtures and the biotoxicity of U. To address these challenges, we present a novel spontaneous microbial electrochemical (SMEC) method that spatially decoupled the microbial oxidation reaction and the U(VI) reduction reaction. Our results demonstrated stable and efficient U extraction with net electrical energy production, which was achieved with both synthetic and real wastewater. U(VI) removal occurred via diffusion-controlled U(VI)-to-U(IV) reduction-precipitation at the cathode, and the UIVO_(2) deposited on the surface of the cathode contributed to the stability and durability of the abiotic U(VI) reduction. Metagenomic sequencing revealed the formation of efficient electroactive communities on the anodic biofilm and enrichment of the key functional genes and metabolic pathways involved in electron transfer, energy metabolism, the TCA cycle, and acetate metabolism, which indicated the ectopic reduction of U(VI) at the cathode. Our study represents a significant advancement in the cost-effective recovery of U from U(VI)-bearing wastewater and may open a new avenue for sustainable uranium extraction.