ELECTRIFIED HIGH-TEMPERATURE MANUFACTURING AND APPLICATIONS IN ENVIRONMENTAL SCIENCE

Abstract

High temperature processes hold great potential for material and chemical manufacturing.On the one hand, high temperature can help overcome energy barriers and thus effectively convert precursors to desired products. On the other hand, high temperature can also boost the reaction rate and improve synthesis efficiency. Recent development of electrified high temperature technologies by our group further revealed the important role played by non-equilibrium conditions on nanomaterial and chemical syntheses. For example, Joule-heating of carbon-based materials through a programmable electrical signal can offer spatial and temporal temperature profiles, which can be used to manipulate the chemical reaction pathways. For another example, tunable heating duration and quenching rates can be used to achieve a range of compositions and structures of nanoparticles. In this dissertation, two specific applications of the electrified high temperature technology will be explored, including: (1) Thermal shock synthesis of multielemental nanoparticles as selective and stable catalysts; and (2) Efficient biomass upgrading via pulsed electrical heating. Supported nanoparticle (NP) catalysts are widely used for various reactions. However, it remains challenging to synthesize high quality NPs with accurate morphologically and structure control. In this part of the research, NP catalysts with morphology or structural design were prepared by high temperature thermal shock methods. Ultra-small and high-loading carbon supported Pt3Ni NPs: Strong electrostatic effect was introduced between metal salts and carbon particles that can largely improve anchoring and dispersion of the precursors, thereby achieving high NP loading (40 wt%) as well as small NP size and good distribution (1.66 ± 0.56 nm). This method is not only limited to bimetallic NPs synthesis or NPs on carbon black but can be extended to a range of NP compositions on various substrate materials, thus providing a general strategy for developing ultrafine and high-loading NPs as electrocatalysts for various reactions. Sustainable aviation fuels (SAFs) are essential to meet future air travel demand while reducing the carbon footprint. Among many potential feedstocks to produce SAFs, lignin stands out as it is an abundant and renewable aromatic biopolymer that is usually treated as a waste material from the paper industry. However, converting lignin to SAFs by conventional thermochemical processes has been challenging due to poor control on the reaction pathway which leads to undesired product distribution. In this study, a programmed electrified heating method was designed and used to break down large lignin molecule to small aromatic molecules with targeted product distribution. A controlled heating step offers sufficient energy input to break down lignin molecules to smaller fragments without excessive secondary reactions toward undesired species such as coke. The lignin thermal decomposition products were evaluated as potential precursor for SAFs generation. This process can be further extended to process other biomass materials such as algae and sawdust to value-added chemicals.