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Iron molybdate synthesis using dicarboxylate decomposition methods for methanol partial oxidation to formaldehyde

Pudge, Geoffrey 2017. Iron molybdate synthesis using dicarboxylate decomposition methods for methanol partial oxidation to formaldehyde. PhD Thesis, Cardiff University.
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Abstract

The formation and subsequent decomposition of iron and molybdenum carboxylate precursors in a molten solvent made of the corresponding carboxylic acid was investigated for the purposes of iron molybdate catalyst production. These catalysts were tested for their ability to partially oxidise methanol to formaldehyde using gaseous oxygen. The use of oxalic acid was tested first and was found to be successful in production of iron molybdate forming highly active catalysts. These samples were found to be highly sensitive to Fe:Mo ratios with the best in terms of formaldehyde yield were 1:2.2 and 1:1.7 due to the superior mixing of iron and molybdenum on the surface and in the bulk content of the catalyst. Other Fe:Mo ratios tested caused non-homogeneous mixing of the iron and molybdenum resulting in lower formaldehyde yields overall. The oxalate method was found to be highly sensitive to water additions into the oxalate mixture with the formation of large quantities of COx selective Fe2O3 with small water additions, large additions caused a more coprecipitation approach to be observed. The use of malonic acid was tested and was found to outperform the oxalic acid examples. This was due to superior mixing of the iron and molybdenum causing a highly homogeneous composition. Similar Fe:Mo study found that a range of ratios(1:1.5, 1:1.9, 1:2.2 and 1:3.0) achieved very high formaldehyde yields. A calcination study showed that the malonate method was highly sensitive to changes in calcination conditions with both composition and performance altered dependent on conditions. Alterations of iron precursor using the malonate method found significant changes in catalyst composition depending on the anion used. Chloride and nitrate were found to be the best achieving very high yields. Acetate, oxalate, sulphate and phosphate were found to produce less homogeneous samples which negatively affected catalytic performance.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Date of First Compliant Deposit: 1 May 2018
Last Modified: 02 May 2018 13:03
URI: http://orca-mwe.cf.ac.uk/id/eprint/111108

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