MIT Unit Affiliation:
Lab Affiliation(s):
Reacting Gas Dynamics Lab
Post Doc Sponsor / Advisor:
Ahmed F. Ghoniem
Areas of Expertise:
  • Transport phenomena
  • Reaction kinetics
  • System analysis
Date PhD Completed:
May, 2017
Expected End Date of Post Doctoral Position:
May 31, 2018

XiaoYu Wu

  • Post Doctoral

MIT Unit Affiliation: 

  • Mechanical Engineering

Lab Affiliation(s): 

Reacting Gas Dynamics Lab

Post Doc Sponsor / Advisor: 

Ahmed F. Ghoniem

Date PhD Completed: 

May, 2017

Top 3 Areas of Expertise: 

Transport phenomena
Reaction kinetics
System analysis

Personal Statement: 

My research interests focus on the fundamental understanding of the kinetics in the thermo-electro-chemical processes under extremely-harsh operating conditions, i.e., high temperature/pressure, supercritical conditions and corrosive environment. Harsh operating conditions are inevitable in many energy and food processing applications such as fusion, combustion, supercritical fluid extraction and membrane filtration. The insights for both the chemical kinetics and process/reactor kinetics, i.e., the reaction kinetics, thermo-fluid transport, material stability and degradation under these conditions are essential for the optimal design of such systems in a safe and efficient manner. Both experimental and simulation tools are used to investigate these processes.

Expected End Date of Post Doctoral Position: 

May 31, 2018

CV: 

Research Projects: 

1. Energy storage: oxygen permeation membranes supporting water/carbon splitting for hydrogen/syngas production at elevated temperatures (link). 

2. Value added chemicals from methane: perovskite oxides replacing precious metal as catalysts for syngas production from methane (link).  

3. Supercritical fluid: heat transfer characteristics of supercritical nanofluid kerosene for regenerative cooling system in engines (link). 

4. Falling film evaporation: enhanced evaporation heat transfer by decreasing liquid film thickness under ultra-low pressure.

Thesis Title: 

Membrane-Supported Hydrogen/Syngas Production using Reactive H2O/CO2 Splitting for Energy Storage

Thesis Abstract: 

Energy storage technologies are crucial for supporting the fast expansion of intermittent renewable energy at the grid scale. One such technology is the efficient and economic conversion of H2O and CO2 into fuels utilizing excess thermal energy at intermediate temperatures. This thesis explores fuel production using oxygen permeable membranes. La0.9Ca0.1FeO3-δ (LCF-91) perovskite is used to develop a framework for reactor design based on a careful assessment of fuel production rate on the membrane design and operating conditions. This material exhibits strong chemical stability but relatively low permeability.

 

Hydrogen production from water splitting is investigated using CH4 to increase the chemical potential gradient across the membrane. Analysis shows that oxygen consumption on the sweep side is the rate limiting step, and the addition of a nickel catalyst on a porous LCF-91 layer on that side raises the hydrogen production rate from water splitting by two orders of magnitude, reaching 0.37 μmol/cm2•s. Raising the oxygen flux suppresses carbon deposition and achieves optimum syngas composition for gas-to-liquid. CO2 splitting was also demonstrated on the same membrane, with similar enhancement as fuel is introduced and porous layers are added on both sides, but at measurably lower rates than water splitting.

 

Based on the experimental data, an oxygen flux model incorporating the surface kinetics and ion transport is developed, in which the oxygen direct-incorporation kinetics are used on the feed-side, and the Mars-van Krevelen (MvK) mechanism for fuel (H2, CO or CH4) oxidation reactions are applied on the sweep-side. The data show that H2 has the lowest activation energy for oxidation among the three fuels, and hence, leads to the highest oxygen flux for H2O/CO2 splitting. Moreover, while the limiting step is always the fuel oxidation in water splitting, it changes from CO formation reactions on the feed-side to fuel oxidation reactions on the sweep-side as the temperature is raised in CO2 splitting.

 

A monolith membrane reactor model based on the reaction kinetics is developed for hydrogen and syngas production from water splitting and partial oxidation of methane, respectively. Results show that the efficiency is ~2% points higher than the conventional steam-methane reforming, when high-purity hydrogen (>99%) is produced. Sensitivity analysis shows that, for the best performance, it is critical to maintain high operating temperatures and high catalytic reactivity for methane oxidation. 

Energy storage technologies are crucial for supporting the fast expansion of intermittent renewable energy at the grid scale. One such technology is the efficient and economic conversion of H2O and CO2 into fuels utilizing excess thermal energy at intermediate temperatures. This thesis explores fuel production using oxygen permeable membranes. La0.9Ca0.1FeO3-δ (LCF-91) perovskite is used to develop a framework for reactor design based on a careful assessment of fuel production rate on the membrane design and operating conditions. This material exhibits strong chemical stability but relatively low permeability.

Hydrogen production from water splitting is investigated using CH4 to increase the chemical potential gradient across the membrane. Analysis shows that oxygen consumption on the sweep side is the rate limiting step, and the addition of a nickel catalyst on a porous LCF-91 layer on that side raises the hydrogen production rate from water splitting by two orders of magnitude, reaching 0.37 μmol/cm2•s. Raising the oxygen flux suppresses carbon deposition and achieves optimum syngas composition for gas-to-liquid. CO2 splitting was also demonstrated on the same membrane, with similar enhancement as fuel is introduced and porous layers are added on both sides, but at measurably lower rates than water splitting.

Based on the experimental data, an oxygen flux model incorporating the surface kinetics and ion transport is developed, in which the oxygen direct-incorporation kinetics are used on the feed-side, and the Mars-van Krevelen (MvK) mechanism for fuel (H2, CO or CH4) oxidation reactions are applied on the sweep-side. The data show that H2 has the lowest activation energy for oxidation among the three fuels, and hence, leads to the highest oxygen flux for H2O/CO2 splitting. Moreover, while the limiting step is always the fuel oxidation in water splitting, it changes from CO formation reactions on the feed-side to fuel oxidation reactions on the sweep-side as the temperature is raised in CO2 splitting.

A monolith membrane reactor model based on the reaction kinetics is developed for hydrogen and syngas production from water splitting and partial oxidation of methane, respectively. Results show that the efficiency is ~2% points higher than the conventional steam-methane reforming, when high-purity hydrogen (>99%) is produced. Sensitivity analysis shows that, for the best performance, it is critical to maintain high operating temperatures and high catalytic reactivity for methane oxidation. 

Top 5 Awards and honors (name of award, date received): 

MIT-France Travel Fellowship, 2017
Best paper initiative in AIChE Journal, 2016
NSF Travel Support Award, 2016
Golden Beaver Award - Institute award for excellence in leadership, MIT, 2016
Best Presentation Award in the 2015 AIChE Annual Meeting, 2015

5 Recent Papers: 

X.Y. Wu, M. Uddi, A.F. Ghoniem, (2016), “Enhancing co-production of H2 and syngas via water splitting and POM on surface-modified oxygen permeable membranes”, AIChE Journal, 62 (12), 4427 - 4435 (invited submission in AIChE Journal “Best paper” initiative)

X.Y. Wu, L. Chang, M. Uddi, P. Kirchen, A.F. Ghoniem, (2016), “Toward enhanced hydrogen generation from water using oxygen permeating LCF membranes”, Physical Chemistry Chemical Physics, 17, 10093-10107 

D. Huang, X. Y. Wu, Z. Wu, H. T. Zhu, W. Li, B. Sunden, (2015), “Experimental Studies on Heat Transfer of Nanofluids in a Vertical tube at Supercritical Pressures“,International Communications in Heat and Mass Transfer, 63, 54-61

Contact Information: