Synthesis and Characterization of Phosphoric Silica Catalyst from Bamboo Leaves for Production of Triacetin

In this research, the bamboo leaf shows promise as an alternative raw material for silica production. This study investigated the performance of heterogeneous catalyst prepared from silica derived bamboo leaf ash after that impregnated with phosphoric acid at ratio various. The catalyst was characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Brunauer Emmet Teller (BET) and Barrett, Joyner and Halenda (BJH) method and triacetin product analyzed by GC-MS. The optimum condition phosphoric silica catalyst was obtained at phosphoric silica molar ratio of 1:2 and employed in the acetylation of glycerol, respectively. As result, 24 % selectivity for triacetin was obtained in the presence of catalytic amount 5%, molar ratio 1:9 at 100 °C for 4 hours. Bamboo leaf derived phosphoric silica calcined showed high potential to be used as an easy to prepare and high-performance solid catalyst for industrial scale.

Synthesis and Chemical Functionalization of Pseudo-Homogeneous Catalysts for Biodiesel Production—Oligocat

With the increase in global demand for biodiesel, first generation feedstock has drawn the attention of governmental institutions due to the correlation with large land farming areas. The second and third feedstock generations are greener feedstock sources, nevertheless, they require different catalytic conditions if compared with first generation feedstock. In this work, we present the synthesis and characterization of oligoesters matrices and their functionalization to act as a pseudo-homogeneous acid catalyst for biodiesel production, named Oligocat. The main advantage of Oligocat is given due to its reactional medium interaction. Initially, oligocat is a solid catalyst soluble in the alcoholic phase, acting as a homogeneous catalyst, providing better mass transfer of the catalytic groups to the reaction medium, and as the course of the reaction happens, Oligocat migrates to the glycerol phase, also providing the advantage of easy separation of the biodiesel. Oligocat was synthesized through polymerization of aromatic hydroxy acids, followed by a chemical functionalization applying the sulfonation technique. Characterization of the catalysts was carried out by infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). The synthesized oligomers presented 5357 g·mol−1 (Mw) and 3909 g·mol−1 (Mn), with a moderate thermal resistance of approximately 175 °C. By sulfonation reaction, it was possible to obtain a high content of sulphonic groups of nearly 70 mol%, which provided the catalytic activity to the oligomeric matrix. With the mentioned physical–chemical properties, Oligocat is chemically designed to convert second generation feedstock to biodiesel efficiently. Preliminary investigation using Oligocat for biodiesel production resulted in conversion rates higher than 96.5 wt.%.

STUDY OF THE PROCESS OF HYDRATION OF MESITYL OXIDE IN THE PRESENCE OF NANOCATALYZERS

The process of mesityl oxide hydrogenation in the presence of a nickel catalyst prepared by impregnating a support with an aqueous solution of the corresponding salt in a displacement reactor in a gas-liquid-solid catalyst system has been studied. It has been established that the use of the catalyst used in the work makes it possible to selectively obtain methyl isobutyl ketone with complete conversion of mesityl oxide in the temperature range 70-100 ºС.

Synthesis of Silica-Based Solid-Acid Catalyst Material as a Potential Osteochondral Repair Model In Vitro

For osteochondral damage, the pH value change of the damaged site will influence the repair efficacy of the patient. For better understanding the mechanism of the acid-base effect, the construction of in vitro model is undoubtedly a simple and interesting work to evaluate the influence. Here, a novel porous silica-based solid-acid catalyst material was prepared by additive manufacturing technology, exhibiting improved eliminating effects of the residue. SEM, FTIR, and TGA were used to characterize the morphology, structure, and thermal stability of the synthesized 3D material. The reaction between 4-methoxybenzyl alcohol and 3, 4-dihydro-2H-pyran was used as a template reaction to evaluate the eliminating performance of the 3D porous material. Solvents were optimized, and three reaction groups in the presence of 3D SiO2, 3D SiO2-SO3H, and 3D SiO2-NH-SO3H, as well as one without catalyst, were compared. In addition, in consideration of the complicated situation of the physiological environment in vivo, universality of the synthesized 3D SiO2-NH-SO3H catalyst material was studied with different alcohols. The results showed that the sulfonic acid-grafted 3D material had excellent catalytic performance, achieving a yield over 95% in only 20 min. Besides, the catalyst material can be recycled at least 10 times, with yields still higher than 90%. Such a solid catalyst material is expected to have great potential in additive manufacturing because the catalyst material is easy-recyclable, renewable and biocompatible. The 3D material with connective channels may also be utilized as an in vitro model for environment evaluation of osteochondral repair in the future.

Application of Pisang Awak Bunch-Derived Heterogenous Base Catalyst in Transesterification of Palm Oil into Biodiesel

Biodiesel is an alternative fuel for diesel machine comprosied of alkyl monoesters deriving from vegetable oils or animal fats. Cooking oil is an oil originated from vegetable or animal fat which has been priorly purified, where it appears in liquid form at room temperature and is usually used to fry food ingredients. Heterogenous catalyst is a catalyst present in different phase with the reagent in a reaction it catalyzes. Kalium content in banana in a banana bunch is sufficiently high reaching 94.4%. The aim of this study was to utilize banana bunch which has been priorly ashed using furnace at 700°C for 4 hours, thereafter, applied as a heterogenous catalyst in a the preparation process of biodiesel from cooking oil. Processing variables investigated in this research included the influences of the number of catalyst (3, 4, 5, 6, and 7%) and molar rasio of oil and methanol (1:5, 1:6, 1:7, 1:8, and 1:9) against the properties of produced biodiesel, namely density, viscosity, and water content which later compred with Indonesian standard (SNI). From the study, it was obtained maximum yield of 90.97% with methanol:oil rasio of 1:7 at processing temperature of 60°C with reaction time of 90 minutes and catalyst as much as 3 % w/w. The characteristics of the cooking oil-based biodiesel obtained from the a reaction with oil: methanol rasio of 1:6 and catalyst as much as 3% w/w were density 850 kg/m3 and viscosity 621 mm2/s. This research showed that the obtained biodiesel characteristics had been sufficient according to the SNI, and the use of calcinated banana bunch was very potential in the production of biodiesel acting as solid catalyst person.

Density Functional Theory Study of Hydrogen Adsorption on Pt Pd/γ-Al2O3 Surface

At present passive hydrogen recombiners (PAR) are used to prevent hydrogen explosion. Hydrogen removal catalyst is the core component of PAR. The adsorption of hydrogen on the solid catalyst surface is the premise of catalytic hydrogen removal and is of great significance for deeper understanding of hydrogen removal mechanism. The adsorption behavior of H2-Pt Pd/γ-Al2O3 system has been studied by using density functional theory and periodic slab model. The results of different adsorption sites indicate the adsorption energy of top site is highest, which is -1.2584eV. Higher adsorption energy means stronger interaction between H2 and catalyst substrate, which elongates H-H bond and increases the negative charge on H2. With increasing doping content of Pd, the adsorption energy of substrate decreases gradually. The adsorption energy absolute value of Pt4/γ-Al2O3 is highest and its H-H bond is longest, arriving at 0.0967nm. After adsorbed on substrate, the energy gap of H2 decreases drastically with the lowest energy gap of H2-Pt4/γ-Al2O3 that is 0.5197eV, and the peaks of density of state pattern move to lower energy level. This is because that the d orbital of Pt/Pd atoms interacts with the τ* anti-bond orbital of H2 strongly, transferring electrons to the τ* anti-bond orbital of H2. Doping Pd increases the energy gap of molecule orbital.

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.

CHEMICAL TRANSFORMATIONS OF ARENES UNDER HYDRODYNAMIC CAVITATION ACTION OF AQUEOUS MEDIA ON ALUMINUM OXIDE

На примере эталонного бензола исследованы химические превращения аренов в водной и водно-кислой среде при гидродинамическом кавитационном воздействии на оксиде алюминия. На основе газовой хроматографии и газовой хроматографии с масс-спектральным детектированием установлено, что ведение процесса на поверхности твёрдого катализатора приводит к образованию н-алканов, алкилзамещенных производных циклогексана, алкилзамещённых моноядерных аренов и полиядерных ароматических соединений. Образующиеся соединения имеют в два-три раза большую, в сравнении с исходным ареном, молекулярную массу. Образование из арена новых классов органических соединений обусловлено интенсивным течением реакций гидрирования, алкилирования и дегедроциклизации. Кислая реакция среды подавляет течение свободно-радикального образования н-алканов. Using the example of reference benzene, the chemical transformations of arenes in an aqueous and aqueous-acid medium under hydrodynamic cavitation action on aluminum oxide are studied. Based on gas chromatography and gas chromatography with mass spectral detection, it was found that conducting the process on the surface of a solid catalyst leads to the formation of n-alkanes, alkyl-substituted cyclohexane derivatives, alkyl-substituted mononuclear arenes and polynuclear aromatic compounds. The resulting compounds have two to three times the molecular weight compared to the initial arene. The formation of new classes of organic compounds from arenes is due to the intensive course of hydrogenation, alkylation and dehedrocyclization reactions. The acidic reaction of the medium suppresses the process of free radical formation of n-alkanes.

Calcium Hydroxyapatite: A Highly Stable and Selective Solid Catalyst for Glycerol Polymerization

Calcium-based catalysts are of high interest for glycerol polymerization due to their high catalytic activity and large availability. However, their poor stability under reaction conditions is an issue. In the present study, we investigated the stability and catalytic activity of Ca-hydroxyapatites (HAps) as one of the most abundant Ca-source in nature. A stochiometric, Ca-deficient and Ca-rich HAps were synthesized and tested as catalysts in the glycerol polymerization reaction. Deficient and stochiometric HAps exhibited a remarkable 100% selectivity to triglycerol at 15% of glycerol conversion at 245 °C after 8 h of reaction in the presence of 0.5 mol.% of catalyst. Moreover, under the same reaction conditions, Ca-rich HAp showed a high selectivity (88%) to di- and triglycerol at a glycerol conversion of 27%. Most importantly, these catalysts were unexpectedly stable towards leaching under the reaction conditions based on the ICP-OES results. However, based on the catalytic tests and characterization analysis performed by XRD, XPS, IR, TGA-DSC and ICP-OES, we found that HAps can be deactivated by the presence of the reaction products themselves, i.e., water and polymers.