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Synthesis of Ethanol from High Pressure Syngas over Rhodium-Based Catalysts

Sheerin, Ephraim A
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397476742

Abstract Details

2014, MS, University of Cincinnati, Engineering and Applied Science: Chemical Engineering.
Strong demand for renewable fuels has focused the world’s attention on alternate methods of energy production. Mobile transportation relies on liquid fuels because of high energy density, easy storage and transportation, and quick refueling. Investigating alternate liquid fuels could solve the problems of supply and cost, providing economic stability to individuals around the world who rely on automobiles. Ethanol is added to gasoline as an oxygenate, but ethanol also can replace gasoline as the main liquid fuel. As governments around the world promote ethanol fuels, the demand is expected to rise. This study focuses on the investigation of several types of heterogeneous catalysts for ethanol synthesis from syngas, which can be derived from many different feedstock such as coal and wood. Rhodium (Rh) is a precious metal that resists deactivation and is highly selective for syngas-to-ethanol reactions. The challenge is to optimize the activity of Rh in order to obtain a high ethanol yield while minimizing Rh loading. This study uses mixed titania and ceria oxides as supports to increase Rh dispersion and activity. Titania and ceria were synthesized using the coprecipatation method. Rh was loaded on the support surface at 2 % (wt. %) using the wet impregnation method. The catalysts were calcined and loaded into a fixed bed reactor at 350 psi from 225 °C to 450 °C where syngas (H2/CO = 2) reacted with a WHSV of 3 h-1 at steady state. The catalysts were characterized using BET, XRD, Raman spectroscopy, TPR, TEM, EDX, and XPS. The TiO2-CeO2 (3:1) mixed oxide support exhibited a specific surface area of 200 m2 g-1 measured by BET. Consequently, this mixed oxide support loaded with 2 % (wt. %) Rh exhibited the highest ethanol selectivity and yield of 40 % and 2 % (carbon mol %), respectively, at 250 °C and exhibited catalytic activity much higher than the pure oxide supported Rh catalysts. This study also investigated Rh loading on mesocellular foams (MCFs). BET confirms very high surface areas of up to 729 m2 g-1. The MCF materials performance widely ranged with a maximum ethanol selectivity of around 65 % and yield of around 3 % (carbon mol %). Surprisingly, MCF supported Rh catalysts exhibited higher ethanol selectivity and yield than mixed oxide supported Rh catalysts despite a lower calculated Rh+1/Rh ratio from XPS spectra. This could be due to ultra-high surface of the MCF resulting in more complete Rh dispersion, but more investigation and study will be needed to optimize and fully understand the Rh/MCF catalytic activity.
Peter Panagiotis Smirniotis, Ph.D. (Committee Chair)
Anastasios Angelopoulos, Ph.D. (Committee Member)
Junhang Dong, Ph.D. (Committee Member)
123 p.
Chemical Engineering
Syngas; Ethanol; MCF; ceria; titania; Rhodium

Recommended Citations

Citations

  • Sheerin, E. A. (2014). Synthesis of Ethanol from High Pressure Syngas over Rhodium-Based Catalysts [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397476742

    APA Style (7th edition)

  • Sheerin, Ephraim. Synthesis of Ethanol from High Pressure Syngas over Rhodium-Based Catalysts. 2014. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397476742.

    MLA Style (8th edition)

  • Sheerin, Ephraim. "Synthesis of Ethanol from High Pressure Syngas over Rhodium-Based Catalysts." Master's thesis, University of Cincinnati, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397476742

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.