Catalytic Dehydration of 1,4‐Butanediol over Mg−Yb Binary Oxides and the Mechanism Study

Abstract

In this study, MgÀ Yb binary oxides were synthesized using different MgO concentrations and investigated for the catalytic dehydration of 1,4-butanediol (BDO) into 3-buten-1-ol (BTO). The physicochemical properties of the catalysts were characterized by N 2 physisorption, X-ray diffraction, Raman spectroscopy, temperature-programmed techniques, and diffuse reflectance infrared Fourier transform spectroscopy. The MgÀ Yb binary oxides exhibited superior catalytic activity and better BTO selectivity compared with the pristine Yb 2 O 3 or MgO. Structures of MgÀ OÀ Yb were generated in the binary oxides via the interchange of Yb or Mg in the MgO or Yb 2 O 3 crystalline phases. Extra basic and acidic sites were formed over the MgÀ Yb binary oxides because of the formation of surface defects and the presence of MgÀ OÀ Yb structures, respectively. The acidic as well as basic sites were observed to influence the catalytic performance: BDO reactivity was enhanced by the more acidic sites, while BTO selectivity was favored by the basic sites. The highest BTO yield of 71.1 % was achieved over the Mg7Yb3 catalyst with 90.4 % BDO conversion and 78.6 % BTO selectivity at 350°C. The in situ DRIFTS results indicated that BDO was first adsorbed on the catalyst and then reacted with the acidic sites to generate butoxides. The β-H of the surface butoxides was abstracted by the basic oxygen anions to produce aldehyde species, which dissociated to form BTO.[a] R.

Continuous Flow Upgrading of Selected C2–C6Platform Chemicals Derived from Biomass

“…Likewise, it was reported that the addition of Yb to magnesium oxide increased the number of acid sites on the catalyst, yet maintaining a high concentration of basic sites. Overall, this contribution of both acidic and basic sites accounted for the performance of the catalyst …”

“…Overall, this contribution of both acidic and basic sites accounted for the performance of the catalyst. 525 2.4.5. Miscellaneous.…”

“…It is currently produced at an industrial level from 1,4-BDO using acid catalysts . The mechanism suggested for the dehydration of 1,4-butanediol into 3-buten-1-ol over heterogeneous catalysts involved the abstraction of a hydrogen in 2-position and the elimination of a terminal hydroxyl group (Scheme b). − …”

“…The gas-phase dehydration of 1,4-BDO into 3-buten-1-ol ( 80 ) was reported over various solid catalysts (Figure ). ,,− ,,,− Elaboration of more complex systems than those used for THF production is required to selectively form 3-buten-1-ol. Indeed, a combination of both acid and basic sites favors the reaction, as the H of 1,4-BDO in the 2-position interacts with basic sites, while acidic sites of the catalyst react with the terminal OH of 1,4-BDO (Scheme ).…”

“…Indeed, a combination of both acid and basic sites favors the reaction, as the H of 1,4-BDO in the 2-position interacts with basic sites, while acidic sites of the catalyst react with the terminal OH of 1,4-BDO (Scheme ). − An alternative redox-based mechanism was proposed upon utilization of ceria as a catalyst. ,, The most relevant catalytic systems and conditions for the gas-phase dehydration of 1,4-BDO into 80 are reported in Table .…”