Acetalization of Glycerol with Citral over Heteropolyacids Immobilized on KIT-6

Glycerol acetalization with citral was studied using a heteropolyacid (tungstophosphoric acid) supported on KIT-6, as a catalyst, at 100 °C. Different catalysts were synthesized. Catalysts were characterized by scanning electron microscopy (SEM), inductively coupled plasma (ICP), X-ray diffraction (XRD), attenuated total refletion-Fourier transform infrared spectroscopy (ATR-FTIR), and potentiometric titrations. At a fixed time, the glycerol conversion increased with the H3PW12O40 (PW) on KIT-6. PW4-KIT-6 material had a higher conversion than other catalysts. The optimization of glycerol’s acetalization with citral was studied under the PW4-KIT-6 catalyst. After 5 h, it was found that, at T = 100 °C, with m = 0.3 g of solid, molar glycerol:citral = 1:2.25, the conversion of glycerol was 89%. Moreover, the PW4-KTI-6 catalyst showed good catalytic stability.

Influence of the Metal Incorporation into Hydroxyapatites on the Deactivation Behavior of the Solids in the Esterification of Glycerol

The effects of the metal incorporation into hydroxyapatites on the deactivation behavior of the solids were examined in the esterification of glycerol (EG) reaction. The introduction of Cu, Co, or Ni ions by ion exchange in calcium-deficient hydroxyapatites resulted in active catalysts for the EG reaction. The metal contents were varied from 2.0 to 17.0%, providing better performances at rather high metal contents. Part of metal species existed in the hydroxyapatite lattice structure and also as isolated Cu2+, Ni2+, and Co2+ entities on the surface, as shown by XPS and EPR. The effects of the reaction temperature, reaction time, and glycerol to acetic acid molar ratios were deeply investigated. The spent solids used in this study were characterized by XRD, FTIR, SEM-EDS, chemical analyses, EPR, and XPS. The Cu2+–OH acid pairs could promote a superior catalytic performance of Cu-containing hydroxyapatites due to the resistance of these solids against leaching of the active species, which is even better than those of Co and Ni-containing counterparts with high metal contents. Cu into hydroxyapatite had a good reusability and long-term utilization for five consecutive cycles of 24 h under a glycerol to acetic acid molar ratio of 0.25 at 80 °C, and longer reaction times provide triacetin formation. This was due to the fact that Cu was stabilized by interacting with Ca, PO4, and OH sites into the hydroxyapatite lattice, being highly active for the EG reaction. The results also revealed that isolated Cu2+ sites played an important role in enhancing the glycerol conversion, intrinsically due to the Cu-containing hydroxyapatites ability to avoid strong adsorption of glycerol oligomers on the catalytic sites.

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).

Synthesis of Glycerol Carbonate from Glycerol and Dimethyl Carbonate Catalyzed by Solid Base Catalyst Derived from Waste Carbide Slag

Na2CO3 was loaded onto waste carbide slag (CS) by impregnation-calcination method to prepare the solid base catalyst, which was used to synthesize glycerol carbonate (GC) by the transesterification of glycerol with dimethyl carbonate (DMC). The prepared catalysts were characterized by a scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunner−Emmet−Teller (BET) techniques. The catalyst 15 wt.% Na2CO3-CS-800, which was prepared by impregnating CS to the Na2CO3 solution with the concentration of 15 wt.% weight of CS and calcined at 800°C for 3 hours, showed an excellent catalytic ability. When it was applied in the catalytic synthesis of GC, 98.1% glycerol conversion and 96.0% GC yield were achieved in 90 mins at 75°C with the catalyst dosage of 3 wt.% to total reactants and the DMC to glycerol molar ratio of 5. More importantly, the loading of Na2CO3 can effectively improve the reusability of catalyst. The 15 wt.% Na2CO3-CS-800 can still achieve 83.6% glycerol conversion and 80.5% GC yield after five-time reuse. Meanwhile, under the same reaction conditions, the CS-800, which was obtained by calcining CS at 800°C for 3 hours, experienced significant activity reduction with only 15.2% glycerol conversion and 14.1% GC yield after five-time reuse. FTIR and XRD characterization revealed that CO32- might play a key role in preserving active catalytic CaO component by forming protective CaCO3 shell on the catalyst surface.

Highly efficient TiO2-supported Co–Cu catalysts for conversion of glycerol to 1,2-propanediol

Glycerol is a low-cost byproduct of the biodiesel manufacturing process, which can be used to synthesize various value-added chemicals. Among them, 1,2-propanediol (1,2-PDO) is of great interest because it can be used as an intermediate and additive in many applications. This work investigated the hydrogenolysis of glycerol to 1,2-PDO over Co–Cu bimetallic catalysts supported on TiO2 (denoted as CoCu/TiO2) in aqueous media. The catalysts were prepared using the co-impregnation method and their physicochemical properties were characterized using several techniques. The addition of appropriate Cu increased the glycerol conversion and the 1,2-PDO yield. The highest 1,2-PDO yield was achieved over a 15Co0.5Cu/TiO2 catalyst at 69.5% (glycerol conversion of 95.2% and 1,2-PDO selectivity of 73.0%). In the study on the effects of operating conditions, increasing the reaction temperature, initial pressure, and reaction time increased the glycerol conversion but decreased the selectivity to 1,2-PDO due to the degradation of formed 1,2-PDO to lower alcohols (1-propanol and 2-propanol). The reaction conditions to obtain the maximum 1,2-PDO yield were a catalyst-to-glycerol ratio of 0.028, a reaction temperature of 250 °C, an initial H2 pressure of 4 MPa, and a reaction time of 4 h.

The Effect of Catalyst Amount & Reacters Comperative on Glycerol Conversion From Castrol Oil With Catalyst Of Pertamina Cracking Process Unit III Palembang

Transesterification of oil with alcohol produces glycerol and methyl esters (biodiesel). The reaction is influenced, among others, by the amount of catalyst and the ratio of oil and meth hanol reagents. This purpose of research to determine the effect of the amount of catalyst and the ratio of reagents on the conversion of glycerol. The experiment was carried out in a three-necked flask equipped with a stirrer and reverse cooling. In a three-necked flask, 150 ml of castor oil was added, 0.375 ml of H2SO4 was added, heated to a temperature of 650C. Then add 185 ml of methanol and stir for 30 minutes. Then let stand 24 hours to form two layers. The bottom layer is glycerol. The transesterification process was continued by adding 100 ml of glycerol in a mixture of methanol (variation 1:2, 1:3, 1:4) with RCC catalyst (variation 1.7gr;1.9gr;2.1gr;2.3gr ;2.5gr) The mixture was then stirred at 90 rpm for 75 minutes. Based on the results of research conducted, the highest glycerol conversion value was in the amount of catalyst 2.1 g with a ratio of reagents between castor oil and methanol of 1:3 of 55.33%.

β-Cyclodextrin-Calcium Complex Intercalated Hydrotalcites as Efficient Catalyst for Transesterification of Glycerol

β-cyclodextrin derivative intercalated MgAl-hydrotalcites (β-CD-Ca/LDH) was synthesized to convert glycerol into high value-added glycerol carbonate(GC) by transesterification of dimethyl carbonate (DMC) and glycerol in this paper. β-cyclodextrin-metal complexes and β-CD-Ca/LDH was characterized by XRD, FT-IR, SEM, XPS and nitrogen adsorption-desorption. The enrichment of organic reactants in the hydrophobic cavity of β-cyclodextrin improved the collision probability of reactants. The intercalation of β-cyclodextrin-calcium complex (β-CD-Ca) increased the pore size and basic strength of catalyst. The experiment results showed that the glycerol conversion was 93.7% and the GC yield was 91.8% catalyzed by β-CD-Ca/LDH when the molar ratio of DMC and glycerol was 3:1, the catalyst dosage was 4 wt.%, the reaction temperature was 75 °C and the reaction time was 100 min while the glycerol conversion was 49.4% and the GC yield was 48.6% catalyzed by MgAl-LDH under the same conditions.

Glycerol Esterification for Triacetin Production using Fe3O4@SiO2@PO43- as Heterogeneous Magnetic Catalyst

To facilitate the magnetic separation, phosphate group is embedded onto silica-coated Fe3O4 magnetic nanoparticles to prepare Fe3O4@SiO2@PO43− solid catalyst for the glycerol esterification with acetic acid. The catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating magnetic spectroscopy (VSM) and Fourier Transform Infrared (FTIR) spectroscopy. The Fe3O4@SiO2@PO43− magnetic catalyst during the glycerol esterification with acetic acid was found to demonstrate excellent glycerol conversion levels (97 %) while retaining 92 % triacetin selectivity. The plausible mechanism of glycerol esterification suggests the initiation of the reaction by the protonation of the acetic acid. The catalyst was recovered from the reaction mixture under the influence of external magnetic field and reused during 4 consecutive reaction cycles.