Session: 17-03: Symposium Steinfeld - Solar fuels via an external energy addition

Paper Number: 142415

142415 - Production of Ethylene via Ethane Dehydrogenation With Thermal Energy Storage Media From Renewable Solar Processes 

Abstract: 

Ethylene production is a carbon-intensive process which results in the emission of 1 – 2 ton CO₂ per ton ethylene produced, or more than half a percent of global anthropogenic CO₂ emissions[1]. Globally, the ethylene market size was estimated at 176 billion USD in 2021 and is projected to grow to 287 billion by 2030[2], making the chemical a high-impact candidate for industrial decarbonization efforts.

The use of thermal energy stored in CarboBead HSP 40/70 and quartz sand media is explored for the goal of the renewable production of ethylene from ethane and other commercially-relevant feed gases. The ethane C₂H₆ dehydrogenation reaction to produce ethylene C₂H₄ is employed, as described by:

C₂H₆ -> C₂H₄ + H₂     (1)

where hydrogen H₂ represents a potential additional value-added chemical if separated and stored. Equation (1) is an endothermic reaction which proceeds in the range of 700 – 800 °C under atmospheric pressure, making it a potential candidate for decarbonization via concentrating solar integration and/or electric heating from renewable sources such as solar photovoltaic or wind. Particle thermal energy storage (PTES) media may be electrically heated or irradiated in a solar receiver and repeatedly used to transfer heat to the EDH reaction directly or indirectly. If integrated with thermal storage, ethane may be renewably and continuously produced outside of daylight hours.

In this work, tube furnace experiments with beds of HSP40/70 and quartz sand were performed to study the impact on the EDH reaction and ethylene yields relative to empty tubes. Ethylene production was detected by mass spectrometry and gas chromatography with evidence that the surface area enhancement provided by the media may have advantages for noncatalytic ethylene production. The kinetics of the EDH reaction were modeled under different temperatures and flow rates. Undesirable side reactions including coking of the PTES bed were evaluated, and quartz sand was found to be more resilient than HSP for multi-cycle operation of the media. The impact of the containment material was also considered by comparing quartz, stainless, and coated stainless tubes in the furnace. Additionally, a thermodynamic systems model of an EDH reactor utilizing moving beds of PTES media, coupled to a solar receiver and PTES components, was developed to predict the relative flows of the solid and gas phases and to identify optimal operating conditions for the cycle in terms of yield and solar input. Future work will include heat and mass transfer models of the EDH reactor subsystem to define a design for commercial scale up and studies on alternative heat transfer media in terms of cost and chemical compatibility with the EDH process.

[1] https://doi.org/10.1021/acscatal.9b02922

[2] https://www.statista.com/statistics/1349781/ethylene-global-market-size/

Presenting Author: Hagan Bush Sandia National Labs

Presenting Author Biography: Dr. H. Evan Bush is an R&D, S&E Mechanical Engineer and Senior Member of the Technical Staff in the Concentrating Solar Technologies group at Sandia National Labs. Evan’s research focuses on solar thermochemical cycles, materials, and reactors for thermal energy storage, H2 generation, and the production of chemical commodities such as ammonia. His research also includes the characterization and control of high-temperature particles for sensible energy transport and storage. Evan has worked on projects relating to CSP systems/technoeconomic modeling; solar reactor engineering and computational modeling; PV solar glint and glare prediction; CSP mirror characterization; and digital imaging and ray tracing to characterize high temperature, high flux systems.

Authors:

Hagan Bush Sandia National Labs
Christopher Riley Sandia National Laboratories
Abhaya Datye University of New Mexico
Andrew De La Riva University of New Mexico
Erik Spoerke Sandia National Laboratories