The effect of zeolite solid acids on the in situ hydrogenation of bio-derived phenol over Raney Ni was investigated, which indicated that the conversion of phenol increased with the addition of zeolite solid acids and Hbeta (Si/Al = 60) showed the best performance of high phenol conversion and selectivity towards the desired products and low carbon loss. In addition, the quantity of Hbeta (Si/Al = 60) and Raney Ni had marked impact on the carbon loss, but little effect on both the conversion and the products distribution. And the mixed catalysts of Raney Ni and Hbeta (Si/Al = 60) exhibited excellent stability.
Rationale Loss of carbon dioxide is an important characteristic fragmentation reaction of deprotonated benzoic acid and its derivatives in electrospray ionization mass spectrometry. However, researchers have rarely noticed or believed that the loss of carbon dioxide in multistage mass spectrometry is a “reversible reaction,” that is, the fragment anion generated by carbon dioxide loss can capture another carbon dioxide to regenerate its precursor ion. Methods The fragmentation of the [M − H] − ions of dicamba (3,6-dichloro-2-methoxybenzoic acid) and benzoic acid was performed with an electrospray ionization hybrid quadrupole-orbitrap mass spectrometer. The structural confirmation of the precursor ions and their product ions was supported by accurate mass (elemental composition) analysis. Pseudo-MS 3 experiments (in-source collision-induced dissociation as MS 2 ) and isotope labelling experiments were used to confirm the addition of carbon dioxide to the product ions in MS 2 . Results In the fragmentation of deprotonated dicamba ( m / z 219), the relative abundance of the precursor ion does not decrease significantly or even increases as the collision energy increases. When the m / z 145 and 175 product ions were isolated in the mass analyzer, the ions 44 m / z units larger ( m / z 189 and 219) were generated spontaneously, indicating the formation of carbon dioxide adduct ions. In the fragmentation of deprotonated [ carboxyl - 13 C]-benzoic acid ( m / z 122), a deprotonated [ carboxyl - 12 C]-benzoic acid ion ( m / z 121) was generated which was derived from 13 CO 2 loss and 12 CO 2 addition. The isotope labelling experiment further supports the formation of CO 2 -attached ions in the fragmentation of deprotonated benzoic acids. Conclusions Under collisional activation, deprotonated dicamba and benzoic acids easily undergo carbon dioxide loss, but the decarboxylated product anions have an appropriate nucleophilicity to carbon dioxide and they can capture a background carbon dioxide molecule remaining in the vacuum system to regenerate the precursor ions. This study provides a new and deeper understanding of the gas-phase chemistry of deprotonated benzoic acid derivatives in mass spectrometry.
Electrochemical carbon dioxide reduction reaction using sustainable energy is a promising approach of synthesizing chemicals and fuels, yet is highly energy intensive. The oxygen evolution reaction is particularly problematic, which is kinetically sluggish and causes anodic carbon loss. In this context, we couple CO 2 electrolysis with hydrogen oxidation reaction in a single electrochemical cell. A Ni(OH) 2 /NiOOH mediator is used to fully suppress the anodic carbon loss and hydrogen oxidation catalyst poisoning by migrated reaction products. This cell is highly flexible in producing either gaseous (CO) or soluble (formate) products with high selectivity (up to 95.3%) and stability (>100 h) at voltages below 0.9 V (50 mA cm −2 ). Importantly, thanks to the “transferred” oxygen evolution reaction to a water electrolyzer with thermodynamically and kinetically favored reaction conditions, the total polarization loss and energy consumption of our H 2 -integrated CO 2 reduction reaction, including those for hydrogen generation, are reduced up to 22% and 42%, respectively. This work demonstrates the opportunity of combining CO 2 electrolysis with the hydrogen economy, paving the way to the possible integration of various emerging energy conversion and storage approaches for improved energy/cost effectiveness.
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