UCLA

As the global energy demand continues to increase, there is a growing focus on the use of renewable electricity as a source of energy to power the transportation, industrial, manufacturing, and commercial/residential sectors of our economy. Although the cost of renewable electricity from wind and solar is decreasing, the world still lacks large scale energy storage technologies that could allow us to use renewable energy even at night or when there is no wind. Fossil fuels are solar energy that was stored millions of years ago. However, fossil fuels are not only the main sources of energy for the residential/commercial and transportation sectors but these are also sources of carbon and hydrogen feedstocks for industrial manufacturing which makes it difficult to abate carbon emissions from these sectors. There is a need to develop sustainable energy generation systems that either replace fossil fuels entirely or that when combined with the use of fossil fuels, diminish the overall greenhouse gas emissions and pave the way for the utilization of clean energy in the future in a manner that is sustainable. This thesis describes research on the use of Joule heating of a FeCr alloy tube washcoated with a Ni/ZrO2 catalysts. Two types of reactions are tested over this catalyst, CO2 methanation and steam methane reforming (SMR). Herein, we describe a systematic study of the catalyst activity, the dependance of performance in temperature, and a description of the temperature profiles generated over the alloy tube during testing. This work describes synthetic routes for the deposition of catalytic washcoats and how deposition parameters affect reactor performance. The results generated in this work, demonstrate that indeed the electrification of traditional chemical reactors is possible and establish a new research capability in the Morales-Guio group. Applying Joule heating to tube reactors provides several benefits compared to radiant and convective heat transfer in industrial reformer furnaces. This thesis work describes the optimization of the washcoating procedure and how these are related to performance. The delivery of heat through Joule heating increases the rate at which energy is provided to the catalysts and influences performance. The catalyst washcoat deposition method influences the active metal mass loading and the washcoat morphology which affects mass transport to the catalytic sites inside the tube surface. Joule heating eliminates thermal gradients between the heat source and the catalysts by decreasing the distance between heat generation and heat consumption on the catalysts. Moreover, it reduces waste gases associated with fuel combustion in furnaces. Finally, the electrified reactor is compact, efficient and amenable to scaling up granted benchmarks of activity and stability are met. Experimental results suggest that there is a difference between external heating and Joule heating of a reactor even when the reactor tube temperature is the same. For both reactions studied in this work, Joule heating methods provide better catalyst performance. Under CO2 Methanation reaction, Joule heating generates a higher methane production rate and also leads to the formation of ethane. For SMR, the activity of the catalyst decreases and could be caused by coke formation. The deactivation mechanism is not well understood in this system and further experiments are required. In summary, Joule heating is a viable approach for the supply of heat in industrially relevant reactions such as SMR and other endothermic processes. The reduced flue gas generation associated with the electrification of furnaces, reduced reactor volume and improvements in catalysts efficiency could provide a unique opportunity for the electrification of industrial chemical production processes. Electrification of chemical manufacturing processes could result in cleaner and more efficient production plants compared to existing chemical manufacturing lines. Electrification of chemical production is an important step towards the decarbonization of the industrial sector and the development of sustainable chemical manufacturing units.