Impact of heterogeneities in silica-supported copper catalysts on their stability for methanol synthesis

Study on the Structure of Cu/SiO2 and Their Catalytic Performance in the Reaction of Phenol Hydroxylation

“…a. Reaction conditions ： 1.0 g phenol,15.0 mL distilled water as solvent, 50 mg catalyst, 1.30 mL H20 2( 3 0 % ) as oxidant, reac tion temperature = 70 Tl , reaction time = 4 h ； b. 5 DHB ： dihydroxybenzenes Selectivity； 5 DHB = mole amount of DHB/ (m ole amounts of HQ+ CAT + BQ + DHB + other) x 100% ； c. FDH B ： dihydroxybenzenes Yields, KnHB = ( mole amount of HQ + mole amount of C A T )/( initial mole amount of phenol) x 100% ; d. HQ: hydroquinone，匕川= mole amount of H Q /( initial mole amount of phenol)x 100% ； CAT： catechol, ^CAT = mole amount of C A T /( initial mole amount of phenol) x 100% ； BQ： />-benzoquinone, FB g = mole amount of B Q /( initial mole amount of phenol) x 100% ； K(>lher= mole amount of o th e r/( initial mole amount of phenol) x 1 〇 〇 % .…”

Carbon-Supported Copper for Gas-Phase Hydrogenation Catalysis

“…The Cu particle size on carbon was much larger than Cu particle sizes on metal oxide supports as reported in literature. 56,72,86,176,216 For example, preparing a sample with 15 wt% Cu on SiO2 previously yielded 2.4 nm Cu particles, using similar synthesis conditions. 86 Furthermore, we observed next to the Cu particles, also sub-nanometer Cu spread over the carbon support (Figure 2.1c).…”

“…[100][101][102][103] The benchmark catalyst for methanol synthesis is co-precipitated Cu/ZnO/Al2O3, with reactions operated at temperatures between 200 and 300 °C and pressures between 40 and 100 bar. 99,104 The activity and stability of Cu-based catalysts for methanol synthesis have been important research topics over the last decades, [105][106][107][108][109][110] also in our research group with recent work by Van den Berg and Pompe et al 56,72,86,[111][112] CO2 + 3 H2 ⇌ CH3OH + H2O ΔH298 K, 1 bar = -50 kJ mol -1 (Eq. 1.1) CO + 2 H2 ⇌ CH3OH ΔH298 K, 1 bar = -91 kJ mol -1 (Eq.…”

“…An additional thermal decomposition or reduction treatment is typically required to obtain metal nanoparticles supported on the support. Precipitation routes are widely applied to prepare Cu-based catalyst with high Cu loadings (>30 wt%) on metal oxide supports, such as Cu/SiO2, [56][57][58] Cu/Al2O3, [59][60] Cu/CeO2, [61][62] Cu/Cr2O4, [63][64] Cu/ZnO/Al2O3 [65][66][67] and Cu/MnO/Al2O3. [68][69] Impregnation and drying is a method to deposit the metal precursor from solution in a porous support material, by either applying a large excess of solution (wet impregnation) or by filling only the support pores (incipient wetness impregnation).…”

“…A final treatment such as reduction, oxidation or sulfidation can be applied, depending on the desired phase for catalysis. Impregnation is widely applied to prepare catalyst with moderate Cu loadings (<20 wt%) on supports such as Al2O3, [70][71] SiO2, 56,[71][72][73] CeO2 71,74 and TiO2. 71,[75][76] Electrostatic adsorption of metal ions from a precursor solution is a well-known synthesis route to obtain high dispersions of precious metals, such as Pd and Pt.…”