Go to  Advanced Search

Please note that cIRcle is currently being upgraded to DSpace v5.1. The upgrade means that the cIRcle service will *not* be accepting new submissions from 5:00 PM on September 1, 2015 until 5:00 PM on September 4, 2015. All cIRcle material will still be accessible during this period. Apologies for any inconvenience.

Activity of Cs (K)-promoted Cu-MgO in the formation of oxygenates from CH₃OH/CO and CO/H₂

Show full item record

Files in this item

Files Size Format Description   View
ubc_2012_fall_goodarznia_shahin.pdf 1.326Mb Adobe Portable Document Format   View/Open
Title: Activity of Cs (K)-promoted Cu-MgO in the formation of oxygenates from CH₃OH/CO and CO/H₂
Author: Goodarznia, Shahin
Degree Doctor of Philosophy - PhD
Program Chemical and Biological Engineering
Copyright Date: 2012
Publicly Available in cIRcle 2012-09-25
Abstract: The selective synthesis of C₂ oxygenates, especially ethanol, from C₁ species such as CH₃OH and synthesis gas (CO/H₂) is of interest as the demand for clean fuels, including biofuels, increases. However, over alkali-promoted Cu-ZnO catalysts the synthesis of C₂ oxygenates occurs with very low selectivity. Previous mechanistic studies suggest that the basic properties and the Cu properties of these catalysts are critical in determining the C₂ oxygenate selectivity. However, the possible synergistic effect of these catalyst properties on the selectivity of C₂ oxygenates is poorly understood. In the present study, Cu-MgO catalysts were investigated since MgO possesses noticeably higher basic properties compared to ZnO. Furthermore to address the knowledge gap in the literature with respect to a synergistic effect between catalyst basic properties and Cu properties on the synthesis of C₂ oxygenates from CH₃OH/CO, MgO, Cu-MgO and Cs (K)-promoted-Cu-MgO catalysts were prepared, characterized and tested at 101kPa and 498-523K. The catalysts had intrinsic basicities of 3.9 – 17.0 μmol CO₂.m⁻², SACu° of < 3 m².g⁻¹ and SACu₂₊ of < 2 m².g⁻¹. The results showed that methyl formate was the dominant C₂ oxygenate, while selectivity to ethanol and acetic acid was low (< 5 C-atom%). At SA_Cu° (< 2 m².g⁻¹), there was an optimum basicity (9.5 µmol CO₂.m⁻²) at which the selectivity to C₂ species and methyl formate reached a maximum. Also, at approximately constant specific basicity (384.5 – 415.9 µmol CO₂.g⁻¹), an increase in SA_Cu°, led to an increase in methyl formate yield, whereas no correlation between SA_Cu₂₊ and methyl formate yield was observed. The 0.5wt%Cs-40wt%Cu-MgO catalyst showed the highest selectivity towards C₂ oxygenates at 101 kPa and was used for high pressure studies to investigate oxygenates synthesis from CO/H₂ at typical industrial conditions (6000-9000kPa and 558-598K). CH₃OH was the dominant produced oxygenate (>66 C-atom%). The reaction kinetics of CH₃OH was studied. The Cs-Cu-MgO catalyst was noticeably less active for the synthesis of oxygenates, compared to a conventional Cs-Cu-ZnO catalyst, which was caused by lower Cu dispersion and weaker Cu-metal oxide interaction in the Cs-Cu-MgO compared to Cs-Cu-ZnO, as well as poor electronic-conductivity and lack of hydrogenation-activity of MgO compared to ZnO.
URI: http://hdl.handle.net/2429/43266
Scholarly Level: Graduate

This item appears in the following Collection(s)

Show full item record

All items in cIRcle are protected by copyright, with all rights reserved.

UBC Library
1961 East Mall
Vancouver, B.C.
Canada V6T 1Z1
Tel: 604-822-6375
Fax: 604-822-3893