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Conference Presentations by Samuel Evans

Research paper thumbnail of A Novel Perovskite Catalyst for Reforming Biogas Displaying Resistance to Sulphur Poisoning

Research paper thumbnail of A Novel Perovskite Catalyst for Reforming Biogas Displaying Negligible Carbon Deposition

Catalytic reforming of methane using carbon dioxide as the oxidant (Eqn. 1) is a reaction of grea... more Catalytic reforming of methane using carbon dioxide as the oxidant (Eqn. 1) is a reaction of great interest for the production of synthesis gas (H2 + CO), since in addition to generating an important chemical feedstock it simultaneously consumes two greenhouse gases. There is particular interest, as well as significant challenges, in combining it with the generation of biogas (CH4 + CO2) through the anaerobic digestion of biomass, a process that is currently significantly underutilised.
CH4 + CO2 ⇌ 2H2 + 2CO (1)
Research into the generation of electricity by direct reforming of methane using carbon dioxide in solid oxide fuel cells has been steadily increasing over the last few years, with much of the focus on using nickel supported yttria stabilised zirconia anodes [1,2]. These materials, however, suffer from severe lifetime issues due to unwanted carbon deposition caused by side reactions (Eqns. 2 and 3) and limited tolerance to sulphur that result in deactivation and limit their commercial viability. This solid formation of carbon blocks catalytically active sites and disrupts fuel distribution at the anode as well as breaking anode micro structure eventually leading to cell failure.
CH4 ⇌ C + 2H2 (2)
2CO ⇌ C + CO2 (3)
An alternative approach to using conventional nickel cermet anodes is to use mixed oxide materials. However, typically such materials show low catalytic activity and poor selectivity towards synthesis gas formation, favouring total oxidation products. In this presentation we show a novel, hydrothermally synthesized perovskite material that reforms biogas with negligible levels of carbon formation regardless of excess methane in the reactant feed. This material has significantly lower tendency to form deleterious carbon without sacrificing reforming activity and has been shown to be catalytically stable for extended periods of time (Fig.1).

Papers by Samuel Evans

Research paper thumbnail of A novel perovskite based catalyst with high selectivity and activity for partial oxidation of methane for fuel cell applications

Solid oxide fuel cells (SOFCs) have the potential to revolutionise the present fuel economy due t... more Solid oxide fuel cells (SOFCs) have the potential to revolutionise the present fuel economy due to their higher fuel conversion efficiency compared with standard heat engines and the possibility of utilizing the heat produced in a combined heat and power system. One of the reasons they have yet to fulfil this potential is that the conventional anode material of choice, a nickel/yttria-stabilised zirconia cermet, requires a high temperature production process and under operating conditions is susceptible to carbon and sulphur poisoning. Perovskite-based materials have been proposed as potential anode materials for SOFCs due to their potentially high electronic conductivity and catalytic properties. One of the problems in realizing this potential has been their low catalytic activity towards methane reforming compared to conventional nickel based cermet materials. A nickel doped strontium zirconate material produced by low temperature hydrothermal synthesis is described which has high activity for methane reforming and high selectivity towards partial oxidation of methane as opposed to total oxidation products. Initial studies show a very low level of carbon formation which does not increase over time.

Research paper thumbnail of Overcoming carbon deactivation in biogas reforming using a hydrothermally synthesised nickel perovskite catalyst

A hydrothermally synthesised nickel-strontium zirconate perovskite is shown to have excellent sel... more A hydrothermally synthesised nickel-strontium zirconate perovskite is shown to have excellent selectivity towards biogas reforming without suffering from deactivation due to carbon formation. Experiments reveal that this material is capable of very efficiently converting methane and carbon dioxide to synthesis gas (hydrogen and carbon monoxide) at relatively low temperatures and, particularly importantly, high methane contents. Under these conditions we find that carbon production is extremely low and more importantly shows no increase over time, even after 10 days of continuous reforming activity. This conversion of a renewable product, using a catalyst prepared by low temperature hydrothermal methods, provides a route to future sustainable hydrogen, and oxygenate and higher hydrocarbon production whilst lowering some greenhouse gas emissions.

Research paper thumbnail of A Novel Perovskite Catalyst for Reforming Biogas Displaying Resistance to Sulphur Poisoning

Research paper thumbnail of A Novel Perovskite Catalyst for Reforming Biogas Displaying Negligible Carbon Deposition

Catalytic reforming of methane using carbon dioxide as the oxidant (Eqn. 1) is a reaction of grea... more Catalytic reforming of methane using carbon dioxide as the oxidant (Eqn. 1) is a reaction of great interest for the production of synthesis gas (H2 + CO), since in addition to generating an important chemical feedstock it simultaneously consumes two greenhouse gases. There is particular interest, as well as significant challenges, in combining it with the generation of biogas (CH4 + CO2) through the anaerobic digestion of biomass, a process that is currently significantly underutilised.
CH4 + CO2 ⇌ 2H2 + 2CO (1)
Research into the generation of electricity by direct reforming of methane using carbon dioxide in solid oxide fuel cells has been steadily increasing over the last few years, with much of the focus on using nickel supported yttria stabilised zirconia anodes [1,2]. These materials, however, suffer from severe lifetime issues due to unwanted carbon deposition caused by side reactions (Eqns. 2 and 3) and limited tolerance to sulphur that result in deactivation and limit their commercial viability. This solid formation of carbon blocks catalytically active sites and disrupts fuel distribution at the anode as well as breaking anode micro structure eventually leading to cell failure.
CH4 ⇌ C + 2H2 (2)
2CO ⇌ C + CO2 (3)
An alternative approach to using conventional nickel cermet anodes is to use mixed oxide materials. However, typically such materials show low catalytic activity and poor selectivity towards synthesis gas formation, favouring total oxidation products. In this presentation we show a novel, hydrothermally synthesized perovskite material that reforms biogas with negligible levels of carbon formation regardless of excess methane in the reactant feed. This material has significantly lower tendency to form deleterious carbon without sacrificing reforming activity and has been shown to be catalytically stable for extended periods of time (Fig.1).

Research paper thumbnail of A novel perovskite based catalyst with high selectivity and activity for partial oxidation of methane for fuel cell applications

Solid oxide fuel cells (SOFCs) have the potential to revolutionise the present fuel economy due t... more Solid oxide fuel cells (SOFCs) have the potential to revolutionise the present fuel economy due to their higher fuel conversion efficiency compared with standard heat engines and the possibility of utilizing the heat produced in a combined heat and power system. One of the reasons they have yet to fulfil this potential is that the conventional anode material of choice, a nickel/yttria-stabilised zirconia cermet, requires a high temperature production process and under operating conditions is susceptible to carbon and sulphur poisoning. Perovskite-based materials have been proposed as potential anode materials for SOFCs due to their potentially high electronic conductivity and catalytic properties. One of the problems in realizing this potential has been their low catalytic activity towards methane reforming compared to conventional nickel based cermet materials. A nickel doped strontium zirconate material produced by low temperature hydrothermal synthesis is described which has high activity for methane reforming and high selectivity towards partial oxidation of methane as opposed to total oxidation products. Initial studies show a very low level of carbon formation which does not increase over time.

Research paper thumbnail of Overcoming carbon deactivation in biogas reforming using a hydrothermally synthesised nickel perovskite catalyst

A hydrothermally synthesised nickel-strontium zirconate perovskite is shown to have excellent sel... more A hydrothermally synthesised nickel-strontium zirconate perovskite is shown to have excellent selectivity towards biogas reforming without suffering from deactivation due to carbon formation. Experiments reveal that this material is capable of very efficiently converting methane and carbon dioxide to synthesis gas (hydrogen and carbon monoxide) at relatively low temperatures and, particularly importantly, high methane contents. Under these conditions we find that carbon production is extremely low and more importantly shows no increase over time, even after 10 days of continuous reforming activity. This conversion of a renewable product, using a catalyst prepared by low temperature hydrothermal methods, provides a route to future sustainable hydrogen, and oxygenate and higher hydrocarbon production whilst lowering some greenhouse gas emissions.