Synthesis of 2-Butanol by Selective Hydrogenolysis of 1,4-Anhydroerythritol over Molybdenum Oxide-Modified Rhodium-Supported Silica

Hydrodeoxygenation of Oxygen-Containing Aromatic Plastic Wastes to Liquid Organic Hydrogen Carriers

To address the global plastic pollution issues and the challenges of hydrogen storage and transportation, we report a system, based on the hydrodeoxygenation (HDO) of oxygen-containing aromatic plastic wastes, from which organic hydrogen carriers (LOHCs) can be derived. We developed a catalytic system comprised of Ru-ReOx /SiO2 +HZSM-5 for direct HDO of polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene oxide (PPO), and their mixtures, to cycloalkanes as LOHCs, with high yields up to 99 %, under mild reaction conditions. The theoretical hydrogen storage capacity reaches ca. 5.74 wt%. The reaction pathway involves depolymerization of PC into C15 aromatics and C15 monophenols by direct hydrogenolysis of the C-O bond between the benzene ring and ester group, and subsequent parallel hydrogenation of C15 aromatics and HDO of C15 monophenols. HDO of cyclic alcohol is the rate-determining step. The active site is Ru metallic nanoparticles with partially covered ReOx species. The excellent performance is attributed to the synergetic effect of oxophilic ReOx species and Ru metallic sites for C-O hydrogenolysis and hydrogenation, and the promotion effect of HZSM-5 for dehydration of cyclic alcohol. The highly efficient and stable dehydrogenation of cycloalkanes over Pt/γ-Al2 O3 confirms that HDO products can act as LOHCs.

Ru-MnOx Interaction for Efficient Hydrodeoxygenation of Levulinic Acid and Its Derivatives

Metal-oxide interaction was widely observed in supported metal catalysts, playing a significant role in tuning the catalytic performance. Here, we reported that the interaction of Ru and MnO_x was able to facilitate the hydrodeoxygenation of levulinic acid (LA) to 2-butanol with a high turnover frequency (1.99 × 10⁶ h^-1), turnover number (4411), and yield (98.8%). Moreover, this catalyst was capable of removing the hydroxymethyl group of lactones and diol with high yields of products. The high activity of the Ru-MnO_x catalyst was due to the strong Ru-MnO_x interaction, which facilitated reduction of Ru oxide to Ru⁰ and Mn oxide to Mn²⁺. The increased fractions of Ru⁰ and Mn²⁺ provided metal and Lewis acid sites, respectively, and therefore facilitated LA hydrodeoxygenation. A linear correlation between the hydrodeoxygenation activity of the Ru-MnO_x catalyst and [Mn²⁺]ln([Ru⁰]) was observed.

Selective hydroconversion of coconut oil-derived lauric acid to alcohol and aliphatic alkane over MoO x -modified Ru catalysts under mild conditions

Molybdenum oxide-modified ruthenium on titanium oxide (Ru-(y)MoO _x /TiO₂; y is the loading amount of Mo) catalysts show high activity for the hydroconversion of carboxylic acids to the corresponding alcohols (fatty alcohols) and aliphatic alkanes (biofuels) in 2-propanol/water (4.0/1.0 v/v) solvent in a batch reactor under mild reaction conditions. Among the Ru-(y)MoO _x /TiO₂ catalysts tested, the Ru-(0.026)MoO _x /TiO₂ (Mo loading amount of 0.026 mmol g^-1) catalyst shows the highest yield of aliphatic n-alkanes from hydroconversion of coconut oil derived lauric acid and various aliphatic fatty acid C6-C18 precursors at 170-230 °C, 30-40 bar for 7-20 h. Over Ru-(0.026)MoO _x /TiO₂, as the best catalyst, the hydroconversion of lauric acid at lower reaction temperatures (130 ≥ T ≤ 150 °C) produced dodecane-1-ol and dodecyl dodecanoate as the result of further esterification of lauric acid and the corresponding alcohols. An increase in reaction temperature up to 230 °C significantly enhanced the degree of hydrodeoxygenation of lauric acid and produced n-dodecane with maximum yield (up to 80%) at 230 °C, H₂ 40 bar for 7 h. Notably, the reusability of the Ru-(0.026)MoO _x /TiO₂ catalyst is slightly limited by the aggregation of Ru nanoparticles and the collapse of the catalyst structure.

Titania-supported molybdenum oxide combined with Au nanoparticles as hydrogen-driven deoxydehydration catalyst of diol compounds

A heterogenous catalyst for deoxydehydration (DODH) reaction was developed using less expensive Mo than Re as the active center. Combination of Mo with anatase-rich TiO2 and Au as the support...

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions

The adsorption of POMs on Rh/SiO₂ in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO₂ at 393-473 K under 1 MPa of H₂. Monovanadium-substituted silicotungstate, α-SiVW₁₁O₄₀^5- (SiVW₁₁), was more readily adsorbed than nonsubstituted silicotungstate, α-SiW₁₂O₄₀^4- (SiW₁₂). After adsorption at 433 K, SiVW₁₁ was desorbed from Rh/SiO₂ by oxidation with Br₂ water without change of the Keggin structure, as evidenced by ⁵¹V NMR. Trivanadium-substituted silicotungstate, α-1,2,3-SiV₃W₉O₄₀^7-, was not stable, and the desorbed species from Rh/SiO₂ by oxidation with Br₂ did not maintain the Keggin structure. The very high temperature for adsorption (473 K) also led to the decomposition of the Keggin structure of SiVW₁₁. An increase in the concentration of SiVW₁₁ in the liquid phase gave a saturation of the amount of desorbable SiVW₁₁, up to five SiVW₁₁ anions per one Rh particle with a 3 nm size. The elemental analysis and W L₃-edge extended X-ray absorption fine structure of Rh/SiO₂ after the adsorption of SiVW₁₁ showed that a part of SiVW₁₁ was decomposed and irreversibly adsorbed as metallic W species incorporated into the surface of Rh metal particles. The amount of decomposed SiVW₁₁ was almost the same as that of SiVW₁₁ adsorbed as the original Keggin structure. The desorbable SiVW₁₁ was probably bonded on the W atom incorporated on the Rh metal particles as the two-electron-reduced form (α-SiV^IIIW₁₁O₄₀^7-).

Selective Hydrogenolysis of Erythritol over Ir-ReOx /Rutile-TiO2 Catalyst

Partial hydrogenolysis of erythritol, which can be produced at large scale by fermentation, to 1,4-butanediol (1,4-BuD) is investigated with Ir-ReO_x /SiO₂ and Ir-ReO_x /rutile-TiO₂ catalysts. In addition to the higher conversion rate over Ir-ReO_x /TiO₂ than over Ir-ReO_x /SiO₂ , which has been also reported for glycerol hydrogenolysis, Ir-ReO_x /TiO₂ showed higher selectivity to 1,4-BuD than Ir-ReO_x /SiO₂ , especially at low conversion levels, leading to high 1,4-BuD productivity of 20 mmol_1,4-BuD  g_Ir ^-1  h^-1 at 373 K (36 % conversion, 33 % selectivity). The productivity based on the noble metal amount is higher than those reported previously, although the maximum yield of 1,4-BuD (23 %) is not higher than the highest reported values. The reactions of various triols, diols and mono-ols are tested and the selectivity and the reaction rates are compared between catalysts and between substrates. The Ir-ReO_x /TiO₂ catalyst showed about twofold higher activity than Ir-ReO_x /SiO₂ in hydrogenolysis of the C-OH bond at the 2- or 3-positions in 1,2- and 1,3-diols, respectively, whereas the hydrogenolysis of C-OH at the 1-position is less promoted by the TiO₂ support. Lowering the loading amount of Ir on TiO₂ (from 4 wt % to 2 or 1 wt %) decreases the Ir-based activity and 1,4-BuD selectivity. Similarly, increasing the loading amount on SiO₂ from 4 wt % to 20 wt % increases the Ir-based activity and 1,4-BuD selectivity, although they remain lower than those for TiO₂ -supported catalyst with 4 wt % Ir. High metal loadings on the support seem to be important.

Erythritol: Another C4 Platform Chemical in Biomass Refinery

The potential of erythritol as a platform chemical in biomass refinery is discussed in terms of erythritol production and utilization. Regarding erythritol production, fermentation of sugar or starch has been already commercialized. The shift of the carbon source from glucose to inexpensive inedible waste glycerol is being investigated, which will decrease the price of erythritol. The carbon-based yield of erythritol from glycerol is comparable to or even higher than that from glucose. The metabolic pathway of erythritol biosynthesis has become clarified: erythrose-4-phosphate, which is one of the intermediates in the pentose phosphate pathway, is dephosphorylated and reduced to erythritol. The information about the metabolic pathway may give insights to improve the productivity by bleeding. Regarding erythritol utilization, chemical conversions of erythritol, especially deoxygenation, have been investigated in these days. Erythritol is easily dehydrated to 1,4-anhydroerythritol, which can be also used as the substrate for production of useful C4 chemicals. C-O hydrogenolysis and deoxydehydration using heterogeneous catalysts are effective reactions for erythritol/1,4-anhydroerythritol conversion.

Tungsten–zirconia-supported rhenium catalyst combined with a deoxydehydration catalyst for the one-pot synthesis of 1,4-butanediol from 1,4-anhydroerythritol

Biomass-derived 1,4-anhydroerythritol is reduced to 1,4-butanediol over a reusable mixture of heterogeneous catalysts, ReO_x–Au/CeO₂ and ReO_x/WO₃–ZrO₂.

Selective Hydrogenolysis of Furfural Derivative 2-Methyltetrahydrofuran into Pentanediol Acetate and Pentanol Acetate over Pd/C and Sc(OTf)3 Cocatalytic System

It is of great significance to convert platform molecules and their derivatives into high value-added alcohols, which have multitudinous applications. This study concerns systematic conversion of 2-methyltetrahydrofuran (MTHF), which is obtained from furfural, into 1-pentanol acetate (PA) and 1,4-pentanediol acetate (PDA). Reaction parameters, such as the Lewis acid species, reaction temperature, and hydrogen pressure, were investigated in detail. ¹ H NMR spectroscopy and reaction dynamics study were also conducted to help clarify the reaction mechanism. Results suggested that cleavage of the primary alcohol acetate was less facile than that of the secondary alcohol acetate, with the main product being PA. A PA yield of 91.8 % (150 °C, 3 MPa H₂ , 30 min) was achieved by using Pd/C and Sc(OTf)₃ as a cocatalytic system and an 82 % yield of PDA was achieved (150 °C, 30 min) by using Sc(OTf)₃ catalyst. Simultaneously, the efficient conversion of acetic esters into alcohols by simple saponification was carried out and led to a good yield.

Supported Molybdenum Catalysts for the Deoxydehydration of 1,4-Anhydroerythritol into 2,5-Dihydrofuran

Efficient deoxygenation strategies are crucial for the valorization of renewable feedstocks. Deoxydehydration (DODH) enables the direct transformation of two adjacent hydroxyl groups into a double bond. Supported molybdenum-based catalysts were utilized for the first time in DODH. MoO_x /TiO₂ showed superior catalytic activity compared to common molybdenum salts. The catalyst efficiently converted 1,4-anhydroerythritol into 2,5-dihydrofuran in the presence of 3-octanol as reducing agent, showing high reproducibility and stability.

Direct Synthesis of Renewable Dodecanol and Dodecane with Methyl Isobutyl Ketone over Dual-Bed Catalyst Systems

For the first time, we demonstrated two integrated processes for the direct synthesis of dodecanol or 2,4,8-trimethylnonane (a jet fuel range C₁₂ -branched alkane) using methyl isobutyl ketone (MIBK) that can be derived from lignocellulose. The reactions were carried out in dual-bed continuous flow reactors. In the first bed, MIBK was selectively converted to a mixture of C₁₂ alcohol and ketone. Over the Pd-modified magnesium- aluminium hydrotalcite (Pd-MgAl-HT) catalyst, a high total carbon yield (73.0 %) of C₁₂ oxygenates can be achieved under mild conditions. In the second bed, the C₁₂ oxygenates generated in the first bed were hydrogenated to dodecanol over a Ru/C catalyst or hydrodeoxygenated to 2,4,8-trimethylnonane over a Cu/SiO₂ catalyst. The as-obtained dodecanol can be used as feedstock in the production of sodium dodecylsulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), which are widely used as surfactants or detergents. The asobtained 2,4,8-trimethylnonane can be blended into conventional jet fuel without hydroisomerization.