Designing a cost-effective and environmentally friendly heterogeneous catalyst for biodiesel production is essential. To achieve this, new 0.3-CaO-MgO/SBA-15 and 0.8-CaO-MgO/SBA-15 catalysts were prepared by the impregnation method. The new 0.3-CaO-MgO/SBA-15 catalyst had higher purity, larger surface area, and pore volume than 0.8-CaO-MgO/SBA-15, resulting in great catalytic activity for biodiesel production by transesterification of rapeseed oil with methanol. A biodiesel yield of 97.8 wt % was attained under the optimal reaction conditions of 5 wt % catalyst concentration, 15:1 methanol/oil molar ratio, 95degree celsius reaction temperature, and reaction time of 4 h. Most of the parameters and properties of the obtained biodiesel correspond to the EN 14212 standard. The 0.3-CaO-MgO/SBA-15 catalyst could be considered a potential candidate for biodiesel production on industrial level application attributed to intriguing properties like cost-effectiveness, ease of synthesis, and environmental greenness.

New NLO active organic molecular glasses were synthesized based on push-pull azobenzene, which was dendronized with 3,5-bis[2-(trityloxy)ethoxy]benzoic acid and pentafluorophenyl groups were added to enchance thermal and NLO properties via Ar-Ar-F interactions. The configuration, where pentafluorophenyl groups containing dendronizing fragment was attached to donor part of azochromophore, was very promising in our recent research, therefore trityl groups containing dendron was added to acceptor part to rise the glass transition temperature of amorphous compound. Effect of one or two pentafluorophenyl groups was investigated and about three times better NLO parameters were obtained when using one pentafluorophenyl group, as it has greater possibility of NLO properties enchanting Ar-Ar-F interactions with neighboring molecules. New convergent method was used to synthesize azobenzene core dendrimer fully functionalized with trityl end groups. Thermal, optical, and NLO properties were compared to previously reported results of dendrimer samples containing both hydroxyl and trityl groups. Full set of trityl end groups resulted in decreased NLO parameters and stability of poled order. Glass transition temperatures of all synthesized molecular glasses were 63-83 degrees C, and thermal destruction temperatures of all synthesized compounds were at least 250 degrees C. NLO coefficient d(33) values were 14-73 pm.V-1.

Extended Abstract The increase in atmospheric carbon dioxide (CO 2 ) leaves a significant impact on the global warming. The current solution highlighted the need to reduce the alarming CO 2 levels. This also includes any sustainable route that utilizes the generated CO 2 gas to a more valuable product [1]. Synthesizing highly value-added industrial products such as methanol through the catalytic CO 2 hydrogenation is a very effective way to reduce CO 2 emissions, since methanol not only is a clean, renewable fuel but also can be used as an intermediate to produce valuable chemicals [2]. Numerous of studies have been made to develop effective catalysts for CO 2 hydrogenation to methanol. Cu-based catalysts, which contain ZnO and Al 2 O 3 are active for methanol synthesis and have been commercially used for more than 50 years, but research for new more active catalysts continues [1]. In our previous studies Cu/ZnO/SBA-15 catalyst has been developed as an active catalyst for methanol producing in a fixed-bed tubular micro-activity reactor (Microactivity-Effi, PID Eng&Tech S.L. ) at 20 bar with H 2 to CO 2 molar ratio 3 to 1. Preparation of Cu/ZnO/SBA-15 catalyst: an aqueous solution of Cu(NO 3 ) 2 ∙2.5H 2 O and Zn(NO 3 ) 2 ∙6H 2 O was prepared and then an aqueous solution of glycine was added to the first to obtain the “impregnation solution” as in [3]. The “impregnation

To develop a method for the preparation of MgO nanoparticles, precatalyst synthesis from magnesium nitrate with ammonia and calcination was performed in presence of PEG in air. Without PEG, the catalysts are inactive. The conversion to hydroxide was performed using a PEG/MgO molar ratio of 1, but, before the calcination, excess of PEG was either saved (PEG1) or increased to 2, 3, or 4 (PEG 2–4). Catalysts were calcined at 400–660 °C and characterized using XRD, N2 adsorption-desorption, TGA, FTIR, and SEM. The FAME yield in the reactions with methanol depend on the PEG ratio used and the calcination temperature. The optimal calcination temperature and highest FAME yield in the 6 h reactions for catalysts PEG1, PEG2, PEG3 and PEG4 were 400 °C, 74%; 500 °C, 80%; 500 °C, 51% and 550 °C, 31%, respectively. The yield dependence on calcination temperature for catalysts with a constant PEG ratio is similar to that of a bell curve, which becomes wider and flatters with an increase in PEG ratio. For most catalysts, the FAME yield increases as the size of the crystallites decreases. The dependence of FAME and the intermediate yield on oil conversion confirms that all catalysts have strong base sites.

The capture and utilization of carbon dioxide (CO2) has been attracting increasing interest. Producing methanol from captured CO2 and renewable hydrogen is one promising route for CO2 utilization because it would introduce recycled carbon to a vast global fuels and chemicals market. It is known that the Cu or Pd based catalysts are highly active for methanol synthesis. In this study, Cu/ZnO/SBA-15/kaolinite catalysts were prepared with Zn loading varying—2.4, varying – 2.4, 1.6 and 0.5 wt%—to 0.5 wt% – to find the optimum amount of Zn in this catalytic system. The catalysts have been characterized using XRD analysis, N2adsorption–desorption analysis and SEM-EDX analysis. The performance of catalysts was evaluated in a fixed-bed tubular micro-activity reactor at 20 bar 250 °C with H2to CO2 molar ratio 3 to 1. The activity tests showed that the amount of Zn loaded has a significant impact on methanol yield - catalysts yield-catalysts with Zn loading 2.4 and 1.6 have approximately 1.7 times higher space–time yield of methanol than catalyst with Zn loading of 0.5 wt%.

The huge contribution of the transportation sector to GHG emissions motivates the search for a sustainable and renewable alternative to fossil fuels. Fischer–Tropsch synthesis (FTS) is a catalytic process to convert synthesis gas into hydrocarbons for the production of fuels and chemicals. However, further development of FTS catalysts is still needed in order to make the process based on renewables economically viable. In this work mesoporous Fe/SBA-15 was synthesized. Two natural clays (hectorite and kaolin) were used as catalyst binders and promoters. The agglomeration with the clays did not disrupt the mesoporous structure of Fe/SBA-15. The effect of the clay and the effect of the catalyst form (i.e. powder or granules) on the FTS performance was investigated at 280 °C and 20 bar. Comparing catalysts agglomerated with kaolin and hectorite, better performance was observed for catalysts containing kaolin. Catalysts in the form of powder showed better performance in CO converted per gram of iron than the same catalysts in the form of granules. Granular catalysts promoted the formation of gaseous products.

- Use of rapeseed soapstock to produce biodiesel is a sustainable choice, because it deals with waste stream use in biofuel synthesis and lowers the use of food grade oil as fuel feedstock. Rapeseed soapstock was acidulated, and fatty acid and glycerides containing acid oil was separated from water phase. Steam distillation – a mild purification method – was used to separate fatty acids from acid oil. Distilled fatty acids were subjected to sulfuric acid catalyzed esterification with methanol. The chosen reaction conditions were: 65 °C temperature, molar ratio of MeOH to FFA 20:1, 7.5 mol% H 2 SO 4 , and a reaction time 1 h. Esterification of distilled fatty acids proceeded with 98.3–98.5% conversion to FAME and product yield 93–95% from theoretical. The esterification reaction conditions were determined using lauric acid as model compound, the catalyst concentration was adjusted to be less than usually reported, so to avoid oxidation and side reactions. Use of ultrasound assisted synthesis was elaborated by comparing reaction of lauric acid at 25 °C temperature in ultrasonic bath and with stirring. Reaction was faster with stirring than use of ultrasound.

Carbon dioxide catalytic hydrogenation to methanol in the presence of nanocatalysts has been recognized as one of the most effective ways to fix and utilize the emitted CO2. In this study, Cu/ZnO/SBA-15 catalyst has been synthesized by three different methods: "impregnation-sol-gel autocombustion" method, impregnation method and direct synthesis method using triblock copolymer Pluronic P123 as a template. Cu/ZnO/SBA-15 catalysts comprising kaolinite clay have been used in CO2 hydrogenation to methanol for the first time to make the methanol synthesis more cost-effective. The performance of catalysts upon hydrogenation of CO2 was evaluated in a fixed-bed tubular micro-activity reactor at 20 bar with H-2 to CO2 molar ratio 3 to 1 and 250 degrees C. Results showed that the highest methanol production, with STY of 36 mg CH(3)OHh(-1)gcat(-1), could be obtained using the catalyst prepared by "impregnation-sol-gel autocombustion". This synthesis method allowed to obtain catalyst with the smallest crystallite size and a good dispersion of the active phase over and into SBA-15. The CO2 conversion reached 15.9%, which is close to conversion level provided by commercial Cu catalyst.

Production and use of biofuels is important to minimize carbon dioxide emissions in the world.One of biofuels -biodiesel -is obtained from vegetable oils in form of fatty acid methyl esters (FAME).Industrially production of biodiesel proceeds by transesterification with methanol and production of by-product glycerol.In order to exclude the glycerol production, we have researched biodiesel synthesis in potassium tert-butoxide catalyzed chemical interesterification reaction with methyl formate and methyl acetate.In order to ensure the scale-up of 50-times the synthesis has been made using flasks from 100 mL volume to 4 L batch reactor.Scale-up process of biofuel synthesis shows that it proceeds without considerable differences in synthesis procedure and composition of products, but the excess reagent evaporation step is more efficient for smaller volumes.Reactions with methyl acetate allow to make full conversion of oil to biofuel, however the FAME content is only 72%, following conditions were used: temperature 55 ºC, 60 minutes, methyl acetate to oil molar ratio 30, catalyst 1M tBuOK in THF, and catalyst to oil molar ratio 0.10.Reactions with methyl formate allow to obtain biofuel with lower yield but containing 93% of FAME, following conditions were used: temperature 30 ºC, 45 minutes, methyl formate to oil molar ratio 36, catalyst 1M tBuOK in tBuOH, and catalyst to oil molar ratio 0.15.Fuel properties were tested for both biofuels obtained in 4 L reactor.Biofuel obtained in reaction with methyl formate showed better properties, although both fuels could be used as diesel fuel additives.The area of using the methyl formate biofuel would be wider, therefore we propose that methyl formate is more promising reagent for synthesis of biodiesel.Obtained different glycerol formates could be a valuable by-product.

CuO on mesoporous silica catalyst was prepared with post synthesis impregnation method, and the effects of Al and Co promoters on CuO/SBA-15/kaolinite catalyst properties and CO2 hydrogenation were studied. The mixing technology with kaolinite clay (containing Al2O3) was used to obtain the granules and to enhance the CO2 conversion to methanol as a product. The performance of all catalysts for catalytic hydrogenation of CO2 was evaluated on a fixed-bed tubular micro-activity reactor at 20 bar and 250°C with H2/CO2 molar ratio 3:1. XRD analysis, N2 adsorption-desorption analysis and SEM-EDX analysis indicated that the mesoporous structure of SBA-15 remains after loading with CuO and promoters, and after mixing with kaolinite clay. Results were compared with results obtained with commercial CuO/Al2O3 catalyst, which showed high MeOH selectivity (78%) during CO2 hydrogenation reaction.

Pyrolysis of buckwheat straw with or without catalysts was investigated using the TGA-FTIR method to determine the influence of nickel and cobalt ferrites on the distribution of pyrolysis products. According to the obtained results, the overall shape of the thermogravimetric and derivative thermogravimetric curves is unchanged in the presence of nickel and cobalt ferrites but different weight losses were observed. All catalysts contribute to the formation of solid residue from BWS pyrolysis. The presence of cobalt ferrites exhibited the highest bio-oil yields, whereas the highest non-condensable gas yield and the lowest bio-oil yield was obtained with the addition of NiFe2O4 (1) catalyst. According to the obtained results, the ability of nickel and cobalt ferrites to catalyze deoxygenation reactions depends on the crystallite size. The nickel or cobalt ferrites with smaller crystallite size (15-22 nm) show a higher ability to catalyzed dehydration reaction than catalysts with larger crystallite size (45-54 nm).

The blends of varying proportions of biodiesel (FAME) containing formate esters of glycerol and 93.0 wt.% fatty acid methyl esters, obtained in an interesterification reaction with methyl formate without further purification, and winter diesel fuel, were prepared, analyzed and compared with winter diesel fuel. The obtained results showed that blends comprising up to 20 vol.% of FAME fulfill the requirements of the standard LVS EN 590 concerning such characteristics as cold flow properties, viscosity, density, and carbon residue. The increase of FAME content worsens the cold flow properties; however, the mixed fuel with 20 vol.% or lower FAME content, according to the cloud point and cold filter plugging point values, remains in the same severe climate "Class 0" group as winter fuel. The carbon residue of mixed fuels raises with increasing FAME content, but stay low and do not exceed the limits of standard for mixtures with FAME percentage up to 20 vol.%. The comparison of mixed fuels containing 20 vol.% of FAME and the same amount of neat biodiesel (99.6 wt.% of fatty acid methyl esters) shows that the difference is negligible. The obtained results have indicated a good potential of FAME obtained in the interesterification reaction with methyl formate without further purification as a diesel fuel additive for up to 20 vol.%.

The blends of varying proportions of biodiesel fuel containing fatty acid methyl esters and triacetin (FAME*), synthesised accordingly to Latvian patent LV 15 373 and summer diesel were prepared, analysed and compared with diesel fuel. The selected fuel properties (viscosity, density, carbon residue and cold flow properties) tested accordingly to standard LVS-EN 14214 have indicated a good potential of FAME*, obtained by synthesis of fatty acid methyl esters (FAME) by simultaneous conversion of glycerol to triacetin as a renewable diesel engine fuel. The results showed that blends containing 5 to 25% of FAME* in summer diesel yielded the properties closely matching that of diesel.Introduction

Pyrolysis plays a vital role in biomass conversion as one of the most promising thermal conversion routes. Solid, liquid and gaseous products are obtained from biomass pyrolysis. The liquid is considered as perspective fuel; however, the direct use of bio-oil as fuel may present many difficulties due to its high viscosity, poor heating value and relative instability. This creates a significant economic barrier for production of transportation fuel by pyrolysis process. Catalytic pyrolysis has been widely used as a convenient method for the direct conversion of biomass into higher quality liquid bio-fuels. Intermediate pyrolysis of cellulose (as a model substance for biomass) with or without catalysts was investigated using TGA-FTIR method in order to determine the influence of zeolite on the relative yield of the compounds. The addition of zeolite with medium and weak acidity increased the production of volatile matter from 86.1% to 88.5% and 88.9% under the catalyst of MCM-41 and ZSM-5 (70). Zeolite with high acidity contributes to the formation of coke and simultaneously causing the deactivation of the catalyst, thus decreasing the volatile matter of cellulose from 86.1% to 83.6% and 83.2% by using H-ZSM-5 (23) and H-ZSM-5 (50). All catalysts showed deoxygenation activity. Zeolites had higher activity in the deoxygenation of compounds containing hydroxyl group than compounds containing carbonyl and carboxyl groups. H-ZSM-5 (23) had a substantial effect on the production of monoaromatic hydrocarbons whereas the yield of olefins notably increased in the presence of ZSM-5 (70).

In this study, the influence of moisture and acids on the content of fatty acid methyl esters and triacetin in the interesterification reaction by using 1M potassium tert-butoxide in tetrahydrofuran as a homogeneous catalyst was investigated. During the interesterification reaction, the presence of moisture causes a larger negative effect than free fatty acids or acetic acid. The highest content of fatty acid methyl esters (77.6 wt%) and triacetin (17.4 wt%) was achieved at methyl acetate to oil molar ratio (MAOMR) 60 and catalyst to oil molar ratio (COMR) 0.05 by using raw materials with moisture and acids content no larger than 0.005% and 0.08%, respectively. During the interesterification reaction, the excess of the catalyst caused the formation of two-layer and its proceeds only by using high-quality raw materials. This fact has never been mentioned in the literature. The upper layer is biodiesel, the lower layer consists of glycerol and glycerol acetates (mono-, di-, and triacetin). The COMR has a more significant effect on the formation of the biodiesel and glycerol acetates layers than MAOMR. The highest yield of glycerol acetates layer (19.4%) has been formed by using MAOMR 60 and COMR 0.3. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Pyrolysis of buckwheat straw with or without catalysts was investigated using the TGA-FTIR method to determine the influence of zinc-containing nanopowders (ZnO, 1.5 % Er2O3/ZnO, 2 % Ag/ZnO, ZnWO4, ZnAl2O4, and Mn-Zn ferrite) on the distribution of pyrolysis products. The presence of ZnWO4, ZnAl2O4, and Mn-Zn ferrite exhibited the highest bio-oil yields, whereas the highest non-condensable gas yield and the lowest bio-oil yield was obtained with the addition of 2 % Ag/ZnO catalyst. According to the obtained results, ZnWO4 promoted the production of oxygen-containing compounds while the presence of 2 % Ag/ZnO presented the highest amounts of hydrocarbons. The 2 % Ag/ZnO shows a greater effect on the production of monocyclic aromatic hydrocarbons but ZnWO4 inhibits the formation of these compounds. The amounts of olefins slightly increased in the presence of ZnWO4 while the ZnO significantly reduced the formation of olefins.

The rate constants of the transesterification reactions of rapeseed oil with methanol, methyl formate, and methyl acetate at room temperature in the presence of homogeneous potassium tert-butoxide in tetrahydrofuran were investigated and mutually compared for the first time. The aim of this study is to ascertain which of these reactants is the most promising in terms of reaction rate and fuel product formation with higher biodiesel yield. As rapeseed oil and methanol are immiscible with each other, the use of tetrahydrofuran as a co-solvent was also investigated to improve the miscibility of the oil and reactant and to exclude mass transfer effects. The pseudo-first-order kinetic model best described the reaction of the oil with methanol, with a reaction rate constant of 1.49 min(-1), whereas the second-order kinetic model best described the reactions with methyl acetate and methyl formate, with reaction rate constants of 6.66 and 4.05 L mol(-1) min(-1), respectively, at 25 degrees C. The best yield of biodiesel was obtained by the interesterification of triglycerides with methyl acetate (86.5%), and the properties of the obtained product conform closely to the biodiesel standard requirements despite the use of mild reaction conditions to save energy.

Production of biodiesel (FAME) via transesterification of triglycerides with methanol in the presence of basic catalysts has largely increased over time despite the low value of the by-product glycerol. Interesterification of the same feedstock with methyl acetate allows to obtain biofuel with higher yield, as the by-product of this reaction, i.e. triacetin, can be included into the fuel composition. Investigation of interesterification with methyl acetate to oil molar ratio 18 at 55 degrees C during 1 h in presence of potassium tert-butoxide solution in tetrahydrofuran shows that after catalyst to oil molar ratio 0.1 slow increase of FAME and a decrease of triacertin content occur. Variation of catalyst to oil molar ratio does not allow to lower the content of intermediates below 19 wt%. An increase of methyl acetate to oil molar ratio from 18 to 65 reduces the mass fraction of intermediates to 9.5% and FAME to triacetin mass ratio to 5.2. The fuel characteristics of obtained products are close to or comply with the requirements of LVS EN 14214, excluding the requirements for FAME and intermediate content and density. The optimal region of methyl acetate to oil molar ratio as the reasonable compromise between the yield of the target products and removable excess of reactant could be from 24 to 40. (C) 2020 Published by Elsevier Ltd.

In this study Fe2O3/SBA-15 catalyst was synthesized via direct synthesis method under acidic conditions using triblock copolymer Pluronic P123 as template, tetraethyl orthosilicate as a silica source and Fe (NO3)3∙9H2O as iron source. Template was removed using extraction and calcination. The obtained catalyst was characterized using XRD analysis, WDXRF spectroscopy, N2 adsorption-desorption analysis and STEM–EDX measurements. Results of catalyst characterization showed that the synthesized Fe2O3/SBA-15 is mesoporous silica with 2D p6mm hexagonal mesostructure loaded with 15.6 wt.% Fe2O3. Average pore size was 6.95 nm, homogeneous immobilized Fe2O3 nanoparticles do not disrupt the porous hexagonal structure of the support.