Aud I. Spjelkavik

Carbon dioxide reforming of methane over lanthanum-modified catalysts in a fluidized-bed reactor

Abstract Nickel on lanthanum-modified aluminas were prepared and tested as catalysts for the CO 2 + CH 4 ⇔ 2CO + 2H 2 reaction in a fluidized-bed reactor. Attrition tests show that lanthanum increases the strength of the carrier significantly. TPR and XRD results indicate that nickel enters into positions in the Al-O spinel blocks of the subsurface LaAl 12 O 19 phase. This results in lower reducibility and thus lower activity for the reforming reaction as compared to nickel on unmodified alumina. While the unmodified catalyst deactivated rapidly under the chosen test conditions, the modified catalysts seem to be stable over several hours. However, the stability is sensitive to the pretreatment conditions of the catalysts.

Forming MOFs into Spheres by Use of Molecular Gastronomy Methods

A novel method utilizing hydrocolloids to prepare nicely shaped spheres of metal-organic frameworks (MOFs) has been developed. Microcrystalline CPO-27-Ni particles are dispersed in either alginate or chitosan solutions, which are added dropwise to solutions containing, respectively, either divalent group 2 cations or base that act as gelling agents. Well-shaped spheres are immediately formed, which can be dried into spheres containing mainly MOF (>95 wt %). The spheronizing procedures have been optimized with respect to maximum specific surface area, shape, and particle density of the final sphere. At optimal conditions, well-shaped 2.5-3.5 mm diameter CPO-27-Ni spheres with weight-specific surface areas <10 % lower than the nonformulated CPO-27-Ni precursor, and having sphere densities in the range 0.8 to 0.9 g cm(-3) and particle crushing strengths above 20 N, can be obtained. The spheres are well suited for use in fixed-bed catalytic or adsorption processes.

Continuous synthesis of the metal—organic framework CPO-27-Ni from aqueous solutions

AbstractA continuous synthesis route of the metal-organic framework (MOF) CPO-27-Ni (also known as Ni2(dhtp), Ni/DOBDC or Ni-MOF-74) from aqueous solutions of the nickel acetate and sodium salt of the 2,5-dihydroxyterephtalate linker using tubular reactor techniques has been developed. When running the reaction at 90 °C, a conversion of above 90% is reached in just 20 min. The resulting MOF has a specific surface area (Brunauer-Emmett-Teller [BET]) of around 1085 m2/g and a powder X-ray diffraction pattern consistent with the known CPO-27-Ni structure. Scanning electron microscopy clearly shows that crystallite sizes around 40 nm are obtained when using the tubular reactor approach, while state-of-the-art batch synthesis in water typically gives micrometer-sized crystallites as product. The tubular reactor setup can be easily up-scaled by parallelization.