Triacetin Production From Glycerol Using Heterogeneous Catalysts Prepared From Peat Clay

Glycerol, an abundant by-product of biodiesel production, is urgently considered to increase its usage. Triacetin produced from glycerol is an important material, used in polyester, cryogenics, cosmetics and as a biodiesel additive. Using homogeneous catalysts in triacetin production involves high product separation costs. The purpose of this study is to synthesize heterogeneous catalysts based on alumina and silica from peat clay for use in the production of triacetin from glycerol. The conversion of glycerol for triacetin production using such alumina and silica catalysts yielded levels of 82.7% and 87.4% respectively. These values were greater than the conversion value of 71.2% using a sulfuric acid homogeneous catalyst. An optimum conversion of 91% was obtained at the mole ratio of glycerol to acetic acid of 8.9. The potential heterogeneous catalysts were confirmed by the results of SEM, XRD and BET characterization. Therefore, the production of triacetin using heterogeneous silica catalyst could be an alternative approach in commercial processes which currently using homogeneous catalysts.

Glycerol; Heterogeneous catalyst; Peat clay; Triacetin

Much attention is being paid to the limitations of fossil energy such as oil and coal, leading to the development of renewable energy.  For the last two decades, alternative fuels have been developed to meet the rapidly increasing energy consumption needs. Biodiesel, one of the promising alternative and renewable fuels, has been viewed with increasing research interest in recent years as a form of renewable energy (Srithar et al., 2017). Tests on the use of biodiesel in diesel engine performance have been conducted (Susila et al., 2012) using a mixture of diesel fuel with biodiesel from vegetable oil sources, i.e rubber seed oil. Engine tests have shown that the B-20 (rubber seed oil methyl ester catalytic method dry wash system) mixture produced the best engine performance at 2550 rpm. The emission levels produced were more environmentally friendly than those from diesel fuel. Biodiesel production would generate about 10% (w/w) glycerol as the main byproduct; in other words, every gallon of biodiesel generates approximately 1.05 pounds of glycerol (San Kong et al., 2016). Glycerol as a by-product  of  biodiesel  products, which  is effective to be a useful  chemical, is needed to reduceenvironmental pollution (Srithar et al., 2017).

A study on glycerol conduct by Saksono et al. (2012) investigated the effectiveness of plasma electrolysis on hydrogen product quantity and energy consumption. Their results showed that an increase in voltage led to increased hydrogen production and energy consumption, and that the addition of glycerol resulted in a decrease in hydrogen production, but an increase in energy consumption. Moreover, according to Slamet et al. (2015), alternative method with metal oxide and non-metallic oxide, which has been developed in the modification of TiO₂ photocatalyst from a mixture of glycerol-water to produce H₂ with conversion from glycerol.Crude glycerol can be utilized for production of pyrolyzed oil using a microwave heating technique with a coconut shell-based activated carbon catalyst. The derived liquid and gaseous pyrolysis products in the range of 15?42% and 55?82% could be potential alternative fuels in combustion systems (Leong et al., 2016). Recently, the conversion of glycerol into products such as triacetin through an esterification process has been under development. Triacetin is of particular interest due to its wide applications in polyester, cryogenics, cosmetics, as an additive in biodiesel, and as a fuel additive to waste cooking biodiesel (Khayoon & Hameed, 2011; San Kong et al., 2016; Zare et al., 2016).

Production of triacetin from glycerol can be easily processed using homogeneous acid catalysts such as H₂SO₄, HCl, HNO₃ or H₃PO₄ (Khayoon & Hameed, 2011). However, the catalyst could cause corrosion in industrial equipment and also have a toxic impact on the environment (San Kong et al., 2016). Moreover, such a catalyst involves a complex separation process, thus contributing to the high costs. Various heterogeneous catalysts have been studied to produce triacetin from glycerol and their efficiencies classified into different groups: ion exchange resin, zeolites, heteropolyacids, metal oxides, mesoporous silica, amberlist, carbon, alumina, zirconia and the nano-silica (SiO2) co-precipitation method using a high-energy grinding technique (Zhou et al., 2012; Jalil et al., 2016; Rane et al., 2016; San Kong et al., 2016). However, the use of these commercial synthesis catalysts has a major disadvantage, its high cost (Zhou et al., 2012). The price of commercial synthesis catalysts in the chemical industry was USD 0.98 – 1.65/kg (San Kong et al., 2016). However, since the industry's needs are growing rapidly, the price of catalysts reaches USD 20-40/kg.

One potential resource that can be considered as a heterogeneous catalyst is peat clay. This is a crystal-shaped and layered structure with particles smaller than 2 µm. It is located under peat soil at a depth of 1.5–3 meters below ground level and contains alumina and silica, hence its potential use as a catalyst or support (Uddin, 2017). The peat clay in South Kalimantan, Indonesia has characteristics such as weight of soil volume of 0.964 g cm^-3; specific gravity of 1.381; void ratio of 6.891; organic contents 95.380%; fiber contents 61.330%; ash content 4.620 %; acidity of pH 3-5; and moisture content 67.732% at 60°C (Nurdin, 2011; Ma'ruf & Yulianto, 2016).

The purpose of this study is to synthesize alumina and silica based heterogeneous catalysts derived from peat clay. The study also characterizes these catalysts, including their catalyst components, crystallinity, pore size and morphology. The catalysts are further tested for the production of triacetin from glycerol and acetic acid.

The authors thank the Graduate Program at Lambung Mangkurat University for supporting the work.

Chen, Z., Weinberger, C., Tiemann, M.,  Kuckling, D., 2017. Organic Polymers as Porogenic Structure Matrices for Mesoporous Alumina and Magnesia. Processes, Volume 5(4), 70,  pp.1-10

Faramawy, S., El-Naggar, A., El-Fadly, A., El-Sabagh, S., Ibrahim, A., 2016. Silica, Alumina and Aluminosilicates as Solid Stationary Phases in Gas Chromatography. Arabian Journal of Chemistry, Volume 9, pp. S765-S775

Hartmann, S., Sachse, A., Galarneau, A., 2012. Challenges and Strategies in the Synthesis of Mesoporous Alumina Powders and Hierarchical Alumina Monoliths. Materials, Volume 5(2), pp. 336-349

Huang, X., Young, N.P., Townley, H.E., 2014. Characterization and Comparison of Mesoporous Silica Particles for Optimized Drug Delivery. Nanomaterials and Nanotechnology, Volume 4(2), pp. 1-15

Jalil, Z., Rahwanto, A., Mulana, F., Mustanir., 2016. Desorption Temperature Characteristic of Mg-based Hydrides Catalyzed by Nano-SiO2 Prepared by High Energy Ball Milling. International Journal of Technology, Volume 7(8), pp. 1301-1306

Khayoon, M., Hameed, B., 2011. Acetylation of Glycerol to Biofuel Additives Over Sulfated Activated Carbon Catalyst. Bioresource Technology, Volume 102(19), pp. 9229-9235

Kuila, U., McCarty, D.K., Derkowski, A., Fischer, T. B., Topór, T., Prasad, M., 2014. Nano-scale Texture and Porosity of Organic Matter and Clay Minerals in Organic-Rich Mudrocks. Fuel, Volume 135, pp. 359-373

Kuila, U., Prasad, M., 2013. Specific Surface Area and Pore-Size Distribution in Clays and Shales. Geophysical Prospecting, Volume 61(2), pp. 341-362

Kusumawati, D.H., Putri, N.P., Hidayat, N., Taufiq, A., Supardi, Z.A.I., 2018. Synthesis and Characterization of ?-Al2O3/SiO2 Composite Materials. Journal of Physics, Volume 1093(Conference 1), pp. 1-7

Leong, S.K., Lam, S.S., Ani, F.N., Ng, J.-H., Chong, C.T., 2016. Production of Pyrolyzed Oil from Crude Glycerol using a Microwave Heating Technique. International Journal of Technology, Volume 7(2), pp 323-331

Ma'ruf, M.A., Yulianto, F.E., 2016. Fibrous Peat Soil: Solutions and Its Problems In Development Of Environmental Infrastructure In: Proceedings of the Geotechnical National Seminar 2016, pp. 279-292

Notodarmojo, S., 2005. Soil and Groundwater Pollution. Bandung: ITB Publisher

Nurdin, S., 2011. Analysis of Changes in Water Content and Shear Strength of Lalombi Peat Soils Due to Effect of Temperature and Heating Time. Smartek, Volume 9(2), pp. 88-108

Pinna, E.G., Suarez, D.S., Rosales, G.D., Rodriguez, M.H., 2017. Hydrometallurgical Extraction of Al and Si From Kaolinitic Clays. REM-International Engineering Journal, Volume 70(4), pp. 451-457

Putra, M.D., Ristianingsih, Y., Jelita, R., Irawan, C., Nata, I.F., 2017. Potential Waste From Palm Empty Fruit Bunches and Eggshells as A Heterogeneous Catalyst For Biodiesel Production. RSC Advances, Volume 7(87), pp. 55547-55554

Rafi, J.M., Rajashekar, A., Srinivas, M., Rao, B., Prasad, R., Lingaiah, N., 2015. Esterification of Glycerol Over a Solid Acid Biochar Catalyst Derived from Waste Biomass. RSC Advances, Volume 5(55), pp. 44550-44556

Rane, S., Pudi, S., Biswas, P., 2016. Esterification of Glycerol with Acetic Acid Over Highly Active and Stable Alumina-based Catalysts: A Reaction Kinetics Study. Chemical and Biochemical Engineering Quarterly, Volume 30(1), pp. 33-45

Ruslan, J.H., Mirzan, M., 2017. Synthesis and Characterization of Sulfated Zirconate Clay Catalyst As A Brass Catalyst In: Proceedings of the National Chemistry Seminar : Synergy of Research and Learning to Support the Development of Chemical Literacy in the Global Era, pp. 325-334

Saksono, N., Ariawan, B., Bismo, S., 2012. Hydrogen Productions System Using Non-Thermal Plasma Electrolysis in Glycerol-KOH Solution. International Journal of Technology, Volume 1(1), pp. 8-15

San Kong, P., Aroua, M.K., Daud, W.M.A.W., Lee, H.V., Cognet, P., Pérès, Y., 2016. Catalytic Role of Solid Acid Catalysts in Glycerol Acetylation for the Production of Bio-additives: A Review. RSC Advances, Volume 6(73), pp. 68885-68905

Segal, F.M., Correa, M.F., Bacani, R., Castanheira, B., Politi, M.J., Brochsztain, S., Triboni, E.R., 2018. A Novel Synthesis Route of Mesoporous ?-Alumina from Polyoxohydroxide Aluminum. Materials Research, Voulme 21(1), pp. 1-8

Setyaningsih, L., Siddiq, F., Pramezy, A. 2018., Esterification of glycerol with acetic acid over Lewatit catalyst In: MATEC Web of Conferences, Volume 154

Slamet, S., Kusrini, E., Salim Afrozi, A., Ibadurrohman, M., 2015. Photocatalytic Hydrogen Production from Glycerol-water over Metal Loaded and Non-metal Doped Titanium Oxide. International Journal of Technology, Volume 6(4), pp 520-532

Srithar, K., Balasubramanian, K.A., Pavendan, V., Kumar, B.A., 2017. Experimental Investigations on Mixing of Two Biodiesels Blended with Diesel as Alternative Fuel for Diesel Engines. Journal of King Saud University-Engineering Sciences, Volume 29(1), pp. 50-56

Susila, I. W., Rachimoellah, R., Sutantra, I., 2012. The Performance of Diesel Engine using Biodiesel Fuel from Rubber Seed Oil Production by Catalytic Method. International Journal of Technology, Volume 3(1), pp. 24-34

Sun, Z.-X., Zheng, T.-T., Bo, Q.-B., Du, M., Forsling, W., 2008. Effects of Calcination Temperature on the Pore Size and Wall Crystalline Structure of Mesoporous Alumina. Journal of Colloid and Interface Science, Volume 319(1), pp. 247-251

Tamborini, L., Militello, M., Balach, J., Moyano, J., Barbero, C., Acevedo, D., 2015. Application of Sulfonated Nanoporous Carbons as Acid Catalysts for Fischer Esterification Reactions. Arabian Journal of Chemistry, Volume 6, pp. 1-11

Uddin, M.K., 2017. A Review on the Adsorption of Heavy Metals by Clay Minerals, with Special Focus on the Past Decade. Chemical Engineering Journal, Volume 308, pp. 438-462

Zare, A., Nabi, M.N., Bodisco, T.A., Hossain, F.M., Rahman, M.M., Ristovski, Z.D., Brown, R.J., 2016. The Effect of Triacetin as a Fuel Additive to Waste Cooking Biodiesel on Engine Performance and Exhaust Emissions. Fuel, Volume 182, pp. 640-649

Zhou, L., Nguyen, T.-H., Adesina, A.A., 2012. The Acetylation of Glycerol Over Amberlyst-15: Kinetic and Product Distribution. Fuel Processing Technology, Volume 104, pp. 310-318