Dual mode plasma UV microreactor for ozonolysis and hydrogenation green chemistry

Ozone is a powerful oxidizing agent but is conventionally expensive to produce, requiring high voltage operation with high power draw, typically produced under vacuum with pure oxygen, cryogenically stored, and unspent, poorly mixed ozone is a hazard that requires expensive, dedicated plant room to destroy. Consequently, ozone is only used when there is no reasonable alternative.We have developed a method for producing ozone at room temperature, atmospheric pressure, from air feedstock, with low voltage operation, high yield, and low power consumption (approximately 1/10th the power draw of conventional plasma reactors with the same throughput), using plasma microreactors. In order to increase the volumetric flow rate, we have multiplexed the microreactors in a dosing lance that delivers the ozone directly into aqueous solution, with dispersal by microbubbles. We are developing this technology for use in the water sector, for applications in water purification and wastewater treatment, where energy efficiency in the production and dispersal of ozone is a strong driver. Our microbubble approach for dispersal should also improve dispersal rates by an order of magnitude, thus minimizing wastage and associated hazards - the level of dosing can be tuned so that all the ozone or intermediates in the production of ozone can be dissolved and consumed in reaction.Plasmolysis formation from steam has always been viewed as an expensive route to hydrogen production, with estimates of 50% efficiency with conventional plasma reactors, trailing behind electrolysis and about on par with thermochemical cycles. In laboratory trials with plasma microreactors, we generated hydrogen from steam with the same conditions as the ozone reaction: room temperature, atmospheric pressure, with low voltage operation,, and low power consumption. Given that it is impossible to achieve a tenfold energy efficiency savings over conventional plasmolysis, the logical conclusion is that some of the heat of reaction is drawn from the steam, and the remainder is the electricity draw. This suggests the potential for substantial energy savings wherever there is a source of waste steam or waste heat to raise steam.Of course, plasmolysis produces H2 and O2 simultaneously and with no space segregation, as in electrolysis. Hence there is a need to separate the products so as to use them separately. Microbubbles provide a sufficient separation due to the fact that hydrogen is practically insoluble in water - oxygen is 25-fold more soluble at room temperature. Hence microbubbles with a tall enough head of water will be practically stripped of oxygen, thus hydrogen rich when they burst at the gas-liquid interface upon rising through a column of water. Since aeration of many wastewaters is a desired processing step, there is every possibility that the hydrogen separation can be achieved while integrated with other processing operations on an industrial plant.With a cheap source of ozone for ozonolysis reactions and hydrogen for hydrogenation reactions, the dosing lance has the potential to yield co-products from biomass processing economically - precursors for bioplastics, nutraceuticals, fine chemicals and pharmaceuticals - from the waste products of agriculture, pulp and paper processing, algal biofuels and biodiesel production, for instance. Although currently petroleum production is highly profitable for the fuel, historically, the introduction of petrochemicals from the bottom of the barrel enormously enhanced the profitability of petrol refining. In order to make bioprocessing to biofuels profitable (and hence sustainable) a similar set of profitable co-products may be necessary. This proposal aims to construct the robust prototype for industrial scale processing of the dosing lance and assess its economic potential for producing co-products.

The major, targeted beneficiary for this proposal is the biomass processing sector. However, there are other applications for the plasma microreactor dosing lance which we are investigating or proposing to investigate in parallel with this proposal: 1. Production of hydrogen / hydrocarbons as en electricity storage medium. Our dosing lance technology is inherently portable and suited to distributed operations. There is an urgent need across all alternative / renewable electricity generation systems for stationary storage. Solar, wind, and wave electricity generation is decorrelated with domestic demand for electricity. A recent study showed that in England, to secure 5GW electricity supply, wind farms generating an average 20GW are required. Suppose the home of the future is outfitted with roof solar panels that produces electricity during the day. Our plasma microreactor system would use this waste electricity to store as hydrogen gas, potentially in a nanobubble storage system or micro/nanofoam storage system, and then use the hydrogen in the evening, feeding it through a fuel cell CHP for electricity and heating. 2. Water and wastewater treatment. Our water sector commercial development partners (AECOM Design Build) have identified more than 20 potential uses in water and wastewater treatment plant - complex organics removal (particularly pesticides), activated carbon remediation, and disinfection are the most common uses, but a cheap and readily applicable source of ozone would find widespread use in other processing stages. 3. Bioreactors. Most bioreactor systems will benefit from breaking down biochemical byproducts in the liquid phase that serve as inhibitors (dual ozone-UV dosing with micro/nanobubble dispersal). This depends on the robustness of the bioculture. Most bioreactors will benefit from a cheap, effective disinfection / sterilization system for the liquid phase with micro/nanobubble dispersal of ozone, for instance. 4. Ozone dosing in HF for cleaning solution for silicon wafers. Cleaning of silicon wafers is a high energy consumption, high water consumption operation, which could be made more efficient and cheaper by adapting the dosing lance to inject ozone-rich micro/nanobubbles into HF aqueous solution for high cleaning effect with low material usage. Potentially, micro/nanofoams would achieve the effect with little waste production. We have recently learned that this may be applicable to the nuclear decontamination of vessels. 5. Lysing of digestate for enhanced anaerobic digester operation. A key limitation in the performance of anaerobic digester limitation is access to the interior of the cells of the biomass. Breaking down the cell walls in biomass by ozone is a significant pre-processing (or perhaps simultaneous) step in accessing the biomaterials internal to the cell, and indeed in many cellulosic materials that make up the cell walls. Although the simultaneous processing may kill a fraction of the bacterial consortium, those that survive will have a much greater food supply available. The current methodology for making the intracellular biomaterials more accessible is effectively a high temperature pressure cooker - energy intensive. The ozone dosing lance technology promises a low energy consumption alternative. The impact plan focuses on the commercial exploitation path for energy efficient micro/nanobubble generation and low power consumption, high yield plasma microreactors (other technology patented by the PI and used in conjunction with microbubble dispersal). The current plan is to spin out a company this year to exploit the greater than 40 industrial contacts in more than ten application areas for these technologies, frequently combined as discussed in the generic beneficiary description. The University of Sheffield has a company incubator (fusionIP) which has been planning the commercial development of these patents over the past 18 months.