Untangling the active sites in the exposed crystal facet of zirconium oxide for selective hydrogenation of bioaldehydes

Abstract

The present study reports the influence of crystal phase, facets, and the active sites of zirconium oxide (ZrO2) on the conversion of bio-aldehydes to corresponding alcohols in isopropanol under mild...

Zr(OH)4‐Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes

“…According to previous literature reports, [10] when adding pyridine into the zirconia-based catalytic system, the pyridine selectively passivates Lewis acidic sites (Zr 4+ )d uring the reaction, thus changing the reaction activity.F or our work, when adding pyridine into the Zr(OH) 4 catalytic systems,i t displayed almost unchanged catalytic activity compared to the pure Zr(OH) 4 catalyst in both peroxide and O 2 systems (Table 3, entry 9), and pure pyridine exhibited no reactivity (Table 3, entry 10). Besides,t he ZrO 2 ,r ich in Lewis acidic sites also showed no reaction activity (Table 3, entry 11).…”

“…Thec hemical states were investigated by XPS analysis (Figure 1(b)), the Zr 3d XPS spectra of Zr(OH) 4 and ZrO 2 both displayed two peaks at around 182 and 184 eV,which could be attributed to the Zr 3d 5/2 and Zr 3d 3/2 respectively,g iving evidence that the Zr chemical state is + 4v alence in both Zr(OH) 4 and ZrO 2 without other chemical valence change. [10] TheFT-IR spectra are exhibited in Figure 1(c), the broad peak at around 3400 cm À1 can be attributed to the stretching vibration of bridging hydroxyl groups and terminal hydroxyl groups in Zr(OH) 4 , [11] which is not visible in the FT-IR spectrum of ZrO 2 .T he bands at 1630 and 1390 cm À1 correspond to the adsorption of CO 2 , [12] and the peak at around 1160 cm À1 is attributed to the Zr À Obond vibration. [13] Moreover,peaks at around 1035 and 750 cm À1 are characteristic of ZrÀOb ond vibrations of crystalline ZrO 2 .…”

Recent advances in the catalytic transfer hydrogenation of furfural to furfuryl alcohol over heterogeneous catalysts

“…Kumar et al investigated the influence of the crystal phase, facets, and active sites of zirconium oxide (ZrO 2 ) on CTH performance. 119 The M–ZrO 2 –U–N catalyst, which was fabricated via a solvothermal process using zirconium oxynitrate and urea as the precursor and precipitant base, respectively, consisted exclusively of the monoclinic crystal phase with the maximum amount of exposed (−111) facet (the crystal facet ratio of (−111)/(111) was 1.51), and gave 92.4% FF conversion and 97.1% FFA selectivity with a TOF of 15.1 h −1 and an E a of 49 kJ mol −1 in isopropanol at 383 K for 6 hours. The catalyst also showed excellent catalytic activity and stability towards the CTH of other bio-aldehydes and ketones to their corresponding alcohols.…”

Advances in the Catalytic Reductive Amination of Furfural to Furfural Amine: The Momentous Role of Active Metal Sites

“…Currently, FUR is obtained from bagasse, or corncob, by acid‐catalyzed reaction via dehydration of xylose, a monomer unit of hemicellulose [17,12b] . The furfural market is driven by the demand for green chemicals and growing industrial applications of various FUR derivatives, such as cyclopentanone, dicarboxylic acid, valerolactone, furfuryl alcohol, tetrahydrofurans, furfural amine, pentanediol, and functionalized aromatics [18a,b] . Various biomass‐derived N‐containing compounds have received considerable attention, and related to this, a few recent Reviews summarize the catalytic and non‐catalytic routes for the synthesis of various N‐containing compounds like pyrroles, pyrrolidones, formamides, pyrazoles, imidazoles, primary amines, pyridine, indoles, and benzimidazoles [18c–e] …”