JCOU 13-2016-71

Tailoring the properties of electrolyzed Ni/mesostructured silica
nanoparticles (MSN) via different Ni-loading methods for CO2
reforming of CH4

A series of Ni/mesostructured silica nanoparticles (NiM) catalysts from an electrolyzed Ni precursor were
prepared by in-situ (NiM_IS), impregnation (NiM_IM), and physical mixing (NiM_PM) methods for CO2
reforming of CH4. N2 physisorption indicated that all preparation methods decreased the surface area and
pore volume of the mesostructured silica nanoparticles (MSN) which may be attributed to the blockage of
the pores by the deposition of NiO particles onto the MSN support. The XRD and H2-TPR analyses
indicated that the in-situ method dispersed smaller Ni0 crystallites and exhibited a stronger metalsupport
interaction compared to the other methods. IR results indicated that the presence of an alkaline
electrolyte during the introduction of Ni promoted sequential desilication-substitution of MSN, forming
Si–O–Ni. CO2 adsorbed IR and ESR spectroscopies showed that NiM_IS possessed a higher basicity and
more defect structures compared to NiM_IM and NiM_PM, owing to the abundant silanol groups and the
formation of metal-deficient Ni2O3. At 800 C, the CH4 and CO2 conversions occur in the order of NiM_IM
(CH4 = 45.6 %, CO2 = 52.4%) <NiM_PM (CH4 = 60.5 %, CO2 = 83.9 %) <NiM_IS (CH4 = 94.3 %, CO2 = 91.7%). The
amount of carbon deposited for NiM_IM, NiM_PM and NiM_IS was 2.97%, 2.35% and 0.84%, respectively.
The promoting effect of the highest catalytic activity and lowest carbon deposition for NiM_IS was related
to an intimate association between better dispersion and strongly interacted Ni, as well as high basicity
and concentration of surface defects in the catalyst.