Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts.

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength

Structural evolution and reaction mechanism of lithium nickelate (LiNiO2) during the carbonation reaction

Lithium nickelate (LiNiO2) was synthesized using the lithium excess method, and then characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption-desorption. Finally, differential thermal and thermogravimetric analyses were performed in CO2 presence, at high temperatures. Results show that LiNiO2 is able to react with CO2 through a complex structural evolution process, where lithium atoms are released to produce Li2CO3, while some nickel atoms are rearranged on different Li1-xNi1+xO2 crystalline phases. LiNiO2-CO2 reaction kinetic parameters were determined assuming a first-order reaction, where kinetic constants tended to increase as a function of temperature. However, kinetic constant values did not follow a linear trend. This atypical behavior was attributed to LiNiO2 sintering and crystalline evolution performed as a function of temperature

Influence of NiO into the CO2 capture of Li4SiO4 and its catalytic performance on dry reforming of methane

Carbon capture, utilization, and storage (CCUS) technology offer promising solution to mitigate the threatening consequences of large-scale anthropogenic greenhouse gas emissions. Within this context, this report investigates the influence of NiO deposition on the Li4SiO4 surface during the CO2 capture process and its catalytic behavior in hydrogen production via dry methane reforming. Results demonstrate that the NiO impregnation method modifies microstructural features of Li4SiO4, which positively impact the CO2 capture properties of the material. In particular, the NiO–Li4SiO4 sample captured twice as much CO2 as the pristine Li4SiO4 material, 6.8 and 3.4 mmol of CO2 per gram of ceramic at 675 and 650 °C, respectively. Additionally, the catalytic results reveal that NiO–Li4SiO4 yields a substantial hydrogen production (up to 55 %) when tested in the dry methane reforming reaction. Importantly, this conversion remains stable after 2.5 h of reaction and is selective for hydrogen production. This study highlights the potential of Li4SiO4 both a support and a captor for a sorption-enhanced dry reforming of methane. To the best of our knowledge, this is the first report showcasing the effectiveness of Li4SiO4 as an active support for Ni-based catalysis in the dry reforming of methane. These findings provide valuable insights into the development of this composite as a dual-functional material for carbon dioxide capture and conversion

Water adsorption properties of Fe(pz)[Pt(CN)4] and the Capture of CO2 and CO

H2O and cyclohexane adsorption properties and the CO2 and CO capture capability of the microporous material Fe(pz)[Pt(CN)4] were examined. This 3D coordination polymer retained its crystallinity and structural stability after all adsorption–desorption experiments (demonstrated by PXRD and BET surface area). Thus, the total water uptake was equal to 14.6 wt % (8.12 mmol g–1) at 90% P/P0, and in comparison to the adsorption of cyclohexane, Fe(pz)[Pt(CN)4] demonstrated a relatively high degree of hydrophilicity. The total cyclohexane uptake of 0.28 mmol g–1, which in comparison to the total water uptake value of 8.12 mmol g–1, corroborated such hydrophilic behavior. Additionally, the CO2 capture was equal to 9.3 wt % for activated Fe(pz)[Pt(CN)4], a higher value in comparison to other lead MOFs such as NOTT-400 (4.4 wt %), despite the fact that the latter exhibits a larger BET surface area (1356 m2 g–1) than Fe(pz)[Pt(CN)4] (BET = 431 m2 g–1). When the CO2 capture capability was measured on a partially water saturated Fe(pz)[Pt(CN)4] sample, we observed a weight gain from 11.7 wt % (only water uptake) to 14.1 wt % (water + CO2). This weight increment (2.4 wt %) was attributed to the oversolubility of CO2. The CO capture on Fe(pz)[Pt(CN)4] showed a total uptake of 4.7 mmol/g after only 20 min, a result comparable to those for MOFs with much higher BET surface areas, such as MOF-74(Mg) (BET = 1957 m2 g–1; 4.4 mmol g–1). Finally, in situ DRIFT experiments exhibited the coordination of CO with open Pt(II) metal sites

Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength