Bio-oil can be obtained via fast pyrolysis of biomass, and typically contains acetic acid (~30 mass %). The acetic acid has often been tested as a model compound for hydrogen production via reforming bio-oil, in which catalysts are a key factor for stable hydrogen production. However, deactivation of catalysts by coking and oxidation hinders the application of the reforming process. Dolomite-derived Ni-based catalysts with Fe additive, MgNi 0.2 Ca 0.8´x Fe x O 2˘δ (x = 0-0.8), were successfully synthesized by the hydrothermal synthesis method, and then tested in auto-thermal reforming (ATR) of acetic acid (AC). The MgNi 0.2 Ca 0.5 Fe 0.3 O 2˘δ catalyst performed a stable reactivity in ATR: the conversion of AC reached 100%, and the H 2 yield remained stable around 2.6 mol-H 2 /mol-AC. The catalysts were characterized by X-ray diffraction (XRD), N 2 physisorption, X-ray photoelectron spectra (XPS), H 2 -temperature-programmed reduction (TPR), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Thermogravimetry (TG); the results show that a periclase-like solid solution of Mg(Ni,Fe)O and lime were formed via the precursors of dolomite and hydrotalcite, and then transformed into Fe-rich Ni-Fe alloy with basic support of MgO-CaO after reduction. The stable Ni 0 spices with basic support can explain the stability and resistance to coking during ATR of AC.

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Abstract:A formic acid modified catalyst, Co 3 O 4 -CeO 2 , was prepared via facile urea-hydrothermal method and applied in CO oxidation. The Co 3 O 4 -CeO 2 -0.5 catalyst, treated by formic acid at 0.5 mol/L, performed better in CO oxidation with T 50 obtained at 69.5˝C and T 100 obtained at 150˝C, respectively. The characterization results indicate that after treating with formic acid, there is a more porous structure within the Co 3 O 4 -CeO 2 catalyst; meanwhile, despite of the slightly decreased content of Co, there are more adsorption sites exposed by acid treatment, as suggested by CO-TPD and H 2 -TPD, which explains the improvement of catalytic performance.

Carbonate cements, such as calcite, dolomite, ferrocalcite and ankerite, play important roles in the formation of pores in sandstones: precipitation of carbonate cements modifies pores and inhibits compaction, while dissolution creates secondary pores. This work proposed a precipitation-dissolution model for carbonate cements-CO2-H2O system by means of ion equilibrium concentration ([M2+], M = Ca, Mg, Fe or Mn) with different factors, such as temperature, depth, pH, , variable rock composition and overpressure. Precipitation-dissolution reaction routes were also analyzed by minimization of the total Gibbs free energy (ΔG). Δ[M2+], the variation of [Ca2+], [Fe2+], [Mg2+] or [Mn2+] for every 100 m of burial depths, is used to predict precipitation or dissolution. The calculation results indicate that the increasing temperature results in decrease of equilibrium constant of reactions, while the increasing pressure results in a relatively smaller increase of equilibrium constant; As a result, with increasing burial depth, which brings about increase of both temperature and pressure, carbonate cements dissolve firstly and produces the maximal dissolved amounts, and then precipitation happens with further increasing depth; For example, calcite is dissolving from 0.0 km to 3.0 km with a maximal value of [Ca2+] at depth of 0.8 km, and then precipitates with depth deeper than 3.0 km. Meanwhile, with an increasing CO2 mole fraction in the gaseous phase from 0.1% to 10.0% in carbonate systems, the aqueous concentration of metal ions increases, e.g., dissolved amount of CaFe0.7Mg0.3(CO3)2 increases and reaches maximum of 1.78 mmol·L-1 and 8.26 mmol·L-1 at burial depth of 0.7 km with CO2 mole fraction of 0.1% and 10.0%, respectively. For the influence of overpressure in the calcite system, with overpressure ranging from 36 MPa to 83 MPa, pH reaches a minimum of 6.8 at overpressure of 51 MPa; meanwhile, Δ[Ca2+] increases slightly from -2.24 mmol·L-1 to -2.17 mmol·L-1 and remains negative, indicating it is also a precipitation process at burial depth of 3.9 km where overpressure generated. The method used in this study can be applied in assessing burial precipitation-dissolution processes and predicting possible pores in reservoirs with carbonate cement-water-carbon dioxide.