Pore structure control in Ni/SiO2 catalysts with both macropores and mesopores

Influence of Ni/SiO2 catalyst preparation methods on hydrogen production from the pyrolysis/reforming of refuse derived fuel

“…However, the surface area for the catalysts prepared by the combined B-HPG method seemed to be increased with the increase of the calcination temperature from 500 to 700 ºC; and reduced at 900 ºC calcination temperature. A similar effect in relation to the surface area was observed by Takahashi et al [18], while increasing the calcination temperature from 500 ºC up to 700 ºC during the preparation of Ni/SiO 2 catalysts by a similar method using a 20 wt.% Ni loading. N 2 adsorption-desorption isotherms of the fresh catalysts are shown in Figure 1.…”

“…Six different Ni/SiO 2 catalysts with 10 wt.% of NiO concentration were prepared by two different methods. The preparation methodology was adapted from the literature for homogeneous precipitation in wet gel (HPG) [15], and combined phase separation and HPG methods [18]. For the HPG method, tetraethoxysilane (TEOS) and nickel nitrate hexahydrate (Ni(NO 3 ) 2 ·6H 2 O) both from Sigma-Aldrich, were used as sources of silica and nickel respectively.…”

“…For the combined phase separation and HPG method, the preparation method was based on that reported by Tomiyama et al [18]. For this procedure the same raw materials were used together with polyethylene oxide (PEO; ACROS Organics), deionised water and a 60wt.% aqueous solution of nitric acid (HNO 3 ; ARISTAR).…”

“…For this procedure the same raw materials were used together with polyethylene oxide (PEO; ACROS Organics), deionised water and a 60wt.% aqueous solution of nitric acid (HNO 3 ; ARISTAR). PEO was used as polymer additive as it has been reported to act as a template, controlling the morphology of macropores [11,16] One of the most important variables to be controlled during the catalysts preparation was the pH, as in this particular case an increase in the pH promotes a ripening of the silica network and a homogeneous deposition of nickel hydroxide [18]. The dried gel was then further dried at 80 ºC, and then the composite was calcined at three different calcination temperatures 500 ºC, 700 ºC and 900 ºC for 3 hours; the prepared catalysts were assigned as B-HPG500, B-HPG700 and B-HPG900; where B refers to the bimodal combined phase separation and HPG method, and their respective calcination temperatures.…”

“…Furthermore, Takahashi and collaborators [18], suggested the addition of a phase separation step after the homogenous precipitation; resulting in a catalyst containing both macropores and mesopores. It was found that by combining both the phase separation and the gelation process, the distribution of pores in the catalyst was greatly affected (see Supplementary Figure S1(b)).…”