Dry reforming of methane using Ni-Ce catalysts supported on a modified mineral clay

摘要

Ni-Ce catalysts supported on mineral clay modified with Al and PVA (polyvinylic alcohol) were synthesized in the presence of microwave radiation. The effect of the nominal quantity of Ce (3,5 and 10wt.%) was analyzed. The catalysts calcined at 800 °C were characterized by elemental chemical analysis, XRD. TPR-H2, TPO and TEM, and evaluated in the reaction of CO2 reforming of methane between 500 and 800 °C, using a mixture of reacting agents of 5/5/40 CH4/CO2/Ar (50mL min~(-1)) without reduction pre-treatment. The XRD showed that the structure of the catalyst is thermally stable while the TPR-H2 suggested the formation of two types of main reducible species that are related with the different environments that Ni may adopt on the surface of the support. The catalysts showed high catalytic activities during two temperature cycles (increase and decrease) and high yields towards CO and H2 with molar ratios between 0.6 and 1.2. The active phase of the catalyst is stable under the conditions of the reaction since sintering was not observed. Ce showed a beneficial effect on the activities and catalytic selectivities of the solids and in the diminution of the production of coke, depending on the nominal quantity. With the increment of the quantity of Ce an increment in the conversions and catalytic selectivities was obtained. The catalyst with 3 wt.%. of Ce showed the lowest levels of coke production. After the catalytic process the main formation of nanotubes of coke on the surface of the catalyst was established.