Rational design of oligomeric MoO3 in SnO2 lattices for selective hydrodeoxygenation of lignin derivatives into monophenols

Assessment of Lewis‐Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

“…This discrepancy between calculated values of THF and pyridine, in this study, was similarly early noticed and published [38] when applying NH 3 and pyridine as probe molecules for the determination of numbers of Lewis and Brönsted acidic sites. THF results, as shown in Table 1 and Figure 4 , are in good agreement with their very low surface area. The surface area (S BET ) of our samples, whether MoO 3 as pure or mixed with 5–30 mol % CdO (wt/wt), agrees with those published in recent works of literature [31,39] in the range of 2.5‐0.7 m 2 ⋅ g −1 . This is an advantage when using THF as a probe molecule in our successful attempt.…”

“…THF results, as shown in Table 1 and Figure 4, are in good agreement with their very low surface area. The surface area (S BET ) of our samples, whether MoO 3 as pure or mixed with 5-30 mol % CdO (wt/wt), agrees with those published in recent works of literature [31,39] in the range of 2.5-0.7 m 2 • g À 1 . This is an advantage when using THF as a probe molecule in our successful attempt.…”

“…The TPR profile of MoO 3 (Figure 2a) shows two major reduction peaks with T max at 683 and 818 °C, corresponding to the reduction of MoO 3 to MoO 2 , then MoO 2 to Mo metal. [31][32][33][34] On the other hand, the TPR profile of CdO (Figure 2e) exhibits a single peak at T max = 638 °C, attributed to the reduction of CdO to Cd metal. [35,36] The addition of 5 mol % CdO to MoO 3 facilitated the reduction of Mo 6 + to Mo 4 + , where T max of the first peak was lowered and appeared at 662 °C rather than 683 °C, while it retarded the reduction of Mo 4 + to Mo metal as T max of the second peak appeared at a higher temperature, that is, 843 °C instead of 818 °C.…”

Selective Demethoxylation of Guaiacols to Phenols using Supported MoO3 Catalysts

“…The use of 5 % MoO 3 /TiO 2 resulted in 97 % conversion of guaiacol and 82 % selectivity to demethoxylated phenolics (including phenol and methyl-, dimethyl-, trimethylphenol). As such, the yield of demethoxylated phenolics is as high as 79 %, which is in the range for precious metal catalysts (PtÀ Sn/CNF/ Inconel, Pd/C, and Au/TiO 2 with 92-99 % conversion and 79-84 % selectivity) [16,17,19] and some best of non-precious metal catalysts reported so far (FeO x /CeO 2 , MoO 3 , and MoO 2 /AC with 96-100 % conversion and 84-97 % selectivity) [23,27,28] for guaiacol demethoxylation. The use of the 5 % MoO 3 /TiO 2 also resulted in the highest phenol yield (38 %) within the catalyst series investigated, including the benchmark Au/TiO 2 (36 %).…”

“…[14,15] Several exploratory catalyst studies for the selective conversion of guaiacol to demethoxylated phenolics have been reported in the literature. Examples are precious metal catalysts like PtÀ Sn/CNF/Inconel, [16] Pd/C, [17] TiO 2 supported Au, Ag, and Ru catalysts [18][19][20][21][22] but also cheaper Fe-based catalysts such as FeO x /CeO 2 , [23] supported Ni catalysts, [24,25] and Mo oxide catalysts [14,[26][27][28][29][30] , as shown in Table 1. Both batch set-up and fixed-bed reactors were used in previous studies.…”