- A comparative study on porous solid acid oxides as catalysts in the esterification of glycerol with acetic acid
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Acid catalysts comprising of porous SiAl, as well as molybdophosphoric heteropolyacid, supported SiAl nanotubes were synthesized. The characterizations were through scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), termoprogrammed ammonia desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR). Esterification of glycerol into acetins reaction was evaluated over two series of SiAl-based solids. Both series displayed very good activity as well as selectivity towards the acetins within a short reaction time. However, porous SiAl deactivated due to acid sites leaching in long-term catalytic runs. The tuning of the loadings of the molybdophosphoric amount on SiAl halloysite nanotubes leads to an increase in the selectivity towards the mono, di, and triacetins. These catalysts were also recycled up to three times, and a 17 percent of conversion and 100 percent of selectivity for triacetin were obtained due to the combination of acidity, stable structure and porosity of the molybdophosphoric supported SiAl nanotubes.
- Araujo, Jesuina C. S.,Campos, Adriana F.,Filho, Josué M.,Freire, Paulo T. C.,Lang, Rossano,Neto, Antonio B. S.,Oliveira, Alcineia C.,Rodriguez-Castellón, Enrique,Sousa, Francisco F. F.
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- Graphene oxide as a facile solid acid catalyst for the production of bioadditives from glycerol esterification
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Graphene oxide (GO) has proved to be a highly active and reusable solid acid catalyst for glycerol esterification with acetic acid in the synthesis of bioadditives diacylglycerol (DAG) and triacylglycerol (TAG). The effects of reaction temperature, molar ratio of acetic acid to glycerol, catalyst amount and reaction time were investigated. A 90.2% combined selectivity of DAG and TAG with complete glycerol conversion was achieved at 120 °C for 6 h over GO. Final characterization shows that the active site of GO is the remaining SO3H group.
- Gao, Xiaoqing,Zhu, Shanhui,Li, Yongwang
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- Esterification of glycerol with acetic acid using double SO 3H-functionalized ionic liquids as recoverable catalysts
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Esterification of glycerol with acetic acid was studied using a series of Bronsted acidic ionic liquids as catalysts. The results indicate that double SO3H-functionalized ionic liquids show high catalytic activity and fair reusability even at very low catalyst loadings, while the conventional non-functionalized ionic liquids show poor activity. The Bronsted acidity-catalytic activity relationships were also investigated and the results showed that the sequence of the catalytic activity observed in the transformation was in good agreement with the Bronsted acidity order determined by the Hammett method. The Royal Society of Chemistry.
- Liu, Xiumei,Ma, Huiyuan,Wu, Yue,Wang, Chang,Yang, Miao,Yan, Peifang,Welz-Biermann, Urs
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- The effect of an electron-withdrawing group in the imidazolium cation: The case of nitro-functionalized imidazolium salts as acidic catalysts for the acetylation of glycerol
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The acetylation of glycerol was achieved with high conversion and selectivity towards triacetin at low temperatures and short reaction times by using acidic imidazolium salts as catalysts. Moreover, the addition of a nitro group to the imidazolium cation affords a much more competent catalyst, indicating a significant effect provided by the simple electronic change in the imidazolium cation. Theoretical calculations revealed increased polarization of the acidic hydrogen bond on the nitrated salts, which may be related to their superior catalytic behavior when compared to the non-functionalized salts. Combining the preliminary experimental and theoretical results, it is possible to suppose that the catalytic activity of acidic imidazolium salts may be better comprehended by its Br?nsted acidities, but other parameters such as hardness, electronegativity, electrophilicity and ion-pair binding energy were also evaluated in order to investigate their effects in the acetylation of glycerol promoted by these acidic imidazolium salts.
- Morais, Eduardo M.,Grillo, Igor B.,Stassen, Hubert K.,Seferin, Marcus,Scholten, Jackson D.
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- A transesterification-acetalization catalytic tandem process for the functionalization of glycerol: The pivotal role of isopropenyl acetate
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At 30 °C, in the presence of Amberlyst-15 as a catalyst, a tandem sequence was implemented by which a pool of innocuous reactants (isopropenyl acetate, acetic acid and acetone) allowed upgrading of glycerol through selective acetylation and acetalization processes. The study provided evidence for the occurrence of multiple concomitant reactions. Isopropenyl acetate acted as a transesterification agent to provide glyceryl esters, and it was concurrently subjected to an acidolysis reaction promoted by AcOH. Both these transformations co-generated acetone which converted glycerol into the corresponding acetals, while acidolysis sourced also acetic anhydride that acted as an acetylation reactant. However, tuning of conditions, mostly by changing the reactant molar ratio and optimizing the reaction time, was successful to steer the set of all reactions towards the synthesis of either a 1?:?1 mixture of acetal acetates (97% of which was solketal acetate) and triacetin, or acetal acetates in up to 91% yield, at complete conversion of glycerol. To the best of our knowledge, a one-pot protocol with such a degree of control on the functionalization of glycerol via transesterification and acetalization reactions has not been previously reported. The procedure was also easily reproduced on a gram scale, thereby proving its efficiency for preparative purposes. Finally, the design of experiments with isotopically labelled reagents, particularly d4-acetic acid and d6-acetone, helped to estimate the contribution of different reaction partners (iPAc/AcOH/acetone) to the formation of final products. This journal is
- Calmanti, Roberto,Perosa, Alvise,Rigo, Davide,Selva, Maurizio
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- Synthesis of bio-additives: Transesterification of ethyl acetate with glycerol using homogeneous or heterogeneous acid catalysts
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A new catalytic route with potential practical interest to sustainable production of bioadditives from glycerol is described. Ethyl acetate was transesterified with glycerol, in the ratio glycerol:EtOAc 1:10, at 25 or 90 °C using 0.1 equiv. of H2SO4 or TsOH, as homogeneous catalysts. H2SO4 led to the total glycerol consumption in 2 h. In the equilibrium, attained in 9 h, 100percent yield of a diacetin:triacetin (55:45) mixture was formed. Using Amberlyst? 15 dry and Amberlyst? 16 wet in 1:30 glycerol:EtOAc ratio and reflux at 90 °C the total glycerol consumption was achieved in 2 and 10h, respectively. The lower reactivity of Amberlyst-16 wet was explained in terms of deactivation of acid sites and decrease in glycerol diffusion to the inner resin pores, both factors caused by adsorbed water. The kinetics of glycerol transformation and product distribution in the equilibrium in relation to the H2SO 4, Amberlyst-15 (dry) and Amberlyst-16 (wet) catalyzed reactions were measured.
- Meireles, Bruno A.,Pereira, Vera Lu?cia P.
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- Heteropolyacid-based ionic liquids as efficient homogeneous catalysts for acetylation of glycerol
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A series of homogeneous catalysts consisting of pyridinium propyl sulfobetaine (PPS), tungstophosphoric acid (TPA), and acetic acid (HOAc) have been synthesized and exploited for catalytic acetylation of glycerol (GL). Their acid properties were characterized by 31P NMR of trimethylphosphine oxide (TMPO) as the probe molecule, and the effects of acidic strength, PPS/TPA, TPA/GL, and HOAc/GL ratios as well as reaction temperature on catalytic performances during acetylation reaction were investigated. These water-tolerable PPS-TPA-HOAc catalysts, which tend to segregate from glycerol acetate products to form distinct biphasic liquid layers spontaneously after the reaction, were found to be highly efficient and durable for acetylation reaction under continuous operation conditions. Typically, a complete GL conversion may be achieved with a superior glycerol triacetate (GTA) selectivity of 86-99%. Moreover, the unique self-separation biphasic characteristics of the catalyst system facilitate facile separation of products and recycling of catalyst, rendering practical industrial applications in acetylation of alcohol.
- Huang, Ming-Yu,Han, Xiao-Xiang,Hung, Chin-Te,Lin, Jann-Chen,Wu, Pei-Hao,Wu, Jung-Chung,Liu, Shang-Bin
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- Development of niobium containing acidic catalysts for glycerol esterification
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Mesoporous silicate and niobiosilicate materials of SBA-15 type were prepared and post-synthesis modified with MPTMS, i.e. (3-mercaptopropyl) trimethoxysilane, followed by oxidation of thiol species. The samples obtained were characterised by different techniques (N2 adsorption/desorption, XRD, elemental and thermal analyses) and applied as catalysts in glycerol esterification with acetic acid. The focus was on the comparison of the role of niobium in the formation of sulphonic species and its stability in the post-synthesis modified materials (prepared within this work) with those, already published, prepared by one-pot synthesis method. The most important finding is that the presence of niobium in the SBA-15 structure improves the efficiency of -SH oxidation by hydrogen peroxide towards sulphonic species like in case of one-pot synthesised samples. However, contrary to the latter samples the presence of niobium does not increase the stability of the modifier (oxidized MPTMS). This has an impact on faster deactivation of samples prepared. Samples prepared with post-synthesis modification exhibit much higher activity in glycerol esterification.
- Trejda, MacIej,Stawicka, Katarzyna,Dubinska, Anna,Ziolek, Maria
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- The role of Nb in the formation of sulphonic species in SBA-15 and MCF functionalised with MPTMS
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Mesoporous silica and niobiosilicate materials of SBA-15 and MCF types were prepared in the presence of MPTMS, i.e. (3-mercaptopropyl)trimethoxysilane and hydrogen peroxide. The samples obtained were characterised by different techniques (N2 adsorption/desorption, XRD, elemental and thermal analyses) and applied as catalysts in glycerol esterification with acetic acid. The role of niobium species on the formation of sulphonic species and stability of organosilane modifier was explored. The most important finding is that the addition of niobium to the synthesis gel improves the efficiency of -SH oxidation by hydrogen peroxide towards sulphonic species. This behaviour is not dependent on the type of structure of mesoporous materials (SBA-15 or MCF). However, the kind of mesoporous solid influences the efficiency of Nb incorporation and on the esterification process. MCF matrix improves the catalytic performance of the MPTMS modified catalyst.
- Trejda, Maciej,Stawicka, Katarzyna,Ziolek, Maria
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- Yttrium-grafted mesostructured SBA-3 catalyst for the transesterification of glycerol with methyl acetate to synthesize fuel oxygenates
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The synthesis of di- and triacetyl glycerol (DAG and TAG) via the transesterification of glycerol with methyl acetate was investigated over series of solid acid catalysts prepared by grafting yttrium, 1-3.5 wt.%, into the framework of SBA-3 support. The p
- Khayoon,Hameed
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- Lanthanum nanocluster/ZIF-8 for boosting catalytic CO2/glycerol conversion using MgCO3as a dehydrating agent
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A lanthanum-modified zeolitic imidazolate framework (La/ZIF-8) was developed to produce glycerol carbonate using CO2and glycerol as raw materials. La/ZIF-8 provides a high catalytic glycerol conversion efficiency owing to its surface-attached nanoclusters of La2O3, which can be viewed as La3+-O2?pairs that strengthen the Lewis basicity and acidity, and the large specific surface area of ZIF-8. The catalytic glycerol conversion and the yield of glycerol carbonate were 46.5% and 35.3%, respectively, using CH3CN as a dehydrating agent. With increase in the amount of CH3CN, the water molecules could react with CH3CN to reduce the selectivity. When an inorganic dehydrating agent, MgCO3, was used to physically adsorb and remove water molecules in the reaction, the selectivity of the reaction could be increased to over 95%, which is the highest ever reported. Reaction kinetics analysis also revealed that the activation energy of using MgCO3(5.4 kJ mol?1) as a dehydrating agent is lower than that using CH3CN (7.8 kJ mol?1). Moreover, the La/ZIF-8 could be recycled and reused at least three times with high catalytic performance. This study provides an effective material with dual Lewis basicity and acidity for CO2/glycerol conversion and significantly improves the catalytic performance using an inorganic dehydrating agent.
- Hu, Chechia,Chang, Chien-Wei,Yoshida, Masaaki,Wang, Ke-Hsuan
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- Glycerol acetylation considering competing dimerization
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Glycerol acetylation is a very interesting reaction for studies of consecutive kinetics. In this short communication, we present a pseudo-homogeneous model for the synthesis of triacetyl glycerol from the reaction of glycerol and acetic acid over strongly acidic Amberlyst-15 and Amberlyst-70 catalysts, considering a dimerization of diacetyl glycerol (DAG) into diglycerol tetraacetate as a parallel reaction and compare the results with a model without side reactions. The best fits were obtained for apparent zeroth-order dimerization and first-order consecutive reactions in the presence of acetic acid in excess and with removal of water. An adaptation was made for DAG. The proposed model shows that the formation of DAG is faster than the consumption of glycerol, which could be an explanation for the occurrence of DAG dimerization instead of other parallel reactions in acetylation.
- Soares, André V.-H.,Kale, Sumeet S.,Armbruster, Udo,Passos, Fabio B.,Umbarkar, Shubhangi B.,Dongare, Mohan K.,Martin, Andreas
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- Selective formation of triacetin by glycerol acetylation using acidic ion-exchange resins as catalyst and toluene as an entrainer
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Esterification of glycerol with acetic acid in the presence of toluene as an entrainer was performed over acidic Amberlyst ion-exchange resins in a batch reactor. Toluene continuously removed the reaction water, thus the chemical equilibrium was effectively shifted; the selectivity for the most desired product triacetin was dramatically increased. The influence of reaction conditions such as reaction time, acetic acid: glycerol molar ratio and catalyst amount were investigated. More than 95% selectivity to triacetin at complete glycerol conversion was obtained. The ion-exchange resin catalysts were reusable in subsequent runs, but due to some deactivation the triacetin yields deteriorated.
- Kale,Umbarkar,Dongare,Eckelt,Armbruster,Martin
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- Glycerol acetins: Fuel additive synthesis by acetylation and esterification of glycerol using cesium phosphotungstate catalyst
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Glycerol acetylation and esterification reactions with acetic anhydride and acetic acid respectively give acetins, in which di and tri acetins are commercially important products used as fuel additives. Acetylation and esterification of glycerol were studied over various solid acid catalysts namely, cesium phosphotungstate, amberlyst-15, H-beta, sulfated zirconia and montmorillonite K-10 under mild reaction conditions. The catalysts were characterized by XRD, FTIR, SEM and acidity measurements. Among all the catalysts evaluated in this study, cesium phosphotungstate showed highest activity with >98% conversion for both the reactions, whereas di and triacetins selectivity was 99.1% for acetylation and 75% for esterification reaction. The catalyst with high Br?nsted acidity gave high activity for both the reactions, whereas selectivity for di and tri acetins depends on nature of active sites.
- Sandesh, Swetha,Manjunathan, Pandian,Halgeri, Anand B.,Shanbhag, Ganapati V.
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p. 104354 - 104362
(2015)
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- Single-pot template-free synthesis of a glycerol-derived C-Si-Zr mesoporous composite catalyst for fuel additive production
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Synthesis of a highly ordered mesoporous acid- as well as metal-functionalized carbon (-SO3H/C-Si-Zr) material is achieved for the first time from a simple single-pot template-free carbonization of low-value bio-derived glycerol. Addition of TEOS to glycerol right before the carbonization was observed to facilitate molecular-level interactions between them to establish C-Si bonding, which eventually leads to the formation of a high surface area mesoporous -SO3H/C-Si composite material. Unlike this, the addition of ZrO(NO3)2·xH2O to glycerol could not have such an effect, but when Zr is used in the presence of TEOS the mixture could successfully produce the -SO3H/C-Si-Zr composite possessing mesoporosity and uniform acidity suitable for bulky tri-acetin production useful for fuel applications. Here TEOS is observed to play two roles, (1) as a surface area and porosity improver of graphitic carbon by its C-Si interaction and (2) as a mediator to involve Zr in the carbon composite structure through its Si-OH group. Thus, the combined inclusion of Zr and Si sources in the glycerol-derived carbon structure could successfully introduce the positive aspects of porosity improvement (by Si) and acidity improvement (by zirconia) in the mixed composite -SO3H/C-Si-Zr to produce the highest ever selectivity of tri-acetin (~94 wt%) from the same low-value bio-derived glycerol by an acetylation reaction. The sustainability of the process lies in the utilization of waste glycerol as a source of the carbon composite, which in turn catalyzes selective low-value glycerol conversion to industrially important fuel additives.
- Al-Muhtaseb, Ala'A H.,Diwakar, Jitendra,Kumar, Saurabh,Saxena, Sandeep K.,Selvamani, Arumugam,Viswanadham, Nagabhatla
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- Acetylation of glycerol over heteropolyacids supported on activated carbon
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The acetylation of glycerol was carried out over dodecatungstophosphoric acid (PW) supported on activated carbon, being the monoacetin, diacetin and triacetin the reaction products. A series of catalysts, with different heteropolyacid loading (from 3.5 to 6.5 wt.%), were prepared. It was observed that the catalytic activity increases with the amount of PW immobilized on the activated carbon, being the PW2-AC (with 4.9 wt.%) the most active sample. However, at high loading of heteropolyacid on the activated carbon, a decrease on the catalytic activity was observed, which can be probably explained due to some hindrance in the activated carbon porous system. All catalysts exhibited good values of selectivity to the diacetin. Catalytic stability of the PW2-AC was also studied by performing consecutives batch runs with the same catalyst sample. After the third batch, it was observed that the catalytic activity stabilized.
- Ferreira,Fonseca,Ramos,Vital,Castanheiro
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- Biodiesel Glycerin Valorization into Oxygenated Fuel Additives
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Current industrial methods of biodiesel production lead to an excess of crude glycerin which requires costly purification before commercialization. Production of oxygenated fuel additives is a potential route for glycerin valorization. Glycerin acetylation was carried out over heterogeneous acid catalysts (15%, glycerol weight basis) using glacial acetic acid (molar ratio = 9). The catalysts, containing different amounts of phosphate species (P/Si from 10 to 20 atomic ratio), were prepared by wet impregnation of commercial silica with aqueous solutions of diammonium phosphate and ortho-phosphoric acid. X-ray diffraction patterns of calcined solids presented amorphous patterns like raw silica. The prepared catalysts presented, at 120?°C, glycerol conversion higher than 89.5% after 1?h of reaction, been diacetin the major product, with triacetin selectivities lower than 26.1%. Diacetin selectivity was found to be almost invariant with catalyst acidity thus underlining the relevance of catalyst porosity due to the large acetins molecules sizes. The slow rate of triacetin diffusion in narrow pores of catalyst might be responsible for the relatively low yield obtained. Surface phosphate species showed a slow rate of leaching in the reaction medium showing high catalyst stability. Graphical Abstract: [Figure not available: see fulltext.]
- Catarino, Mónica,Gomes Fonseca, Frederico,Gomes, Jo?o,Soares Dias, Ana Paula
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- A highly active and stable organic-inorganic combined solid acid for the transesterification of glycerol under mild conditions
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Solid acid catalyst plays a crucial role in the petroleum refinery industry and bio-refinery technology. In this work, p-phenolsulfonic acid (PSA) was successfully grafted onto the surface of KH560-modified zirconium phosphate (K-ZrP) in a facile routine. The structure and property of this organic-inorganic combined solid acid PSA/K-ZrP-x were characterized via XRD, FTIR, 13C solid-state NMR, TG, N2 adsorption-desorption, SEM, pyridine-adsorption FTIR and XPS technologies. The characterization results showed that KH560 can bond with ZrP and promote the grafting of PSA on the surface of K-ZrP via the condensation reaction between its epoxy ring and the phenolic hydroxyl group in PSA. Consequently, PSA/K-ZrP-2 exhibited excellent performance and stability in the transesterification between glycerol and methyl acetate among the tested H3PW12O40, Amberlyst-45, HBEA, HZSM-5, ZrP, AlCl3 and FeCl3 catalysts. The calculated conversion of glycerol reached 81.3% with a 97.9% selectivity for monoacetin (MAG) and diacetin (DAG) with a 2.2% dosage of [H+] at 100 °C for 4 h. The highest specific activity of PSA/K-ZrP-2 reached 24028.2 mg-glycerol/g-cat/h in a short reaction time (at 0.17 h), and it could be recycled five times without obvious deactivation.
- Hou, Zhaoyin,Jiang, Yuanyuan,Long, Yihua,Wang, Zhengbao,Ye, Boyong,Zhao, Huaiyuan,Zhou, Ruru
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p. 1772 - 1781
(2021/06/28)
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- Understanding the role of Keggin type heteropolyacid catalysts for glycerol acetylation using toluene as an entrainer
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The heterogeneously catalyzed esterification (acetylation) of glycerol toward triacetin in batch mode in presence of toluene as entrainer was studied. Silicotungstic acid, tungstophosphoric acid and phosphomolybdic acid as heteropolyacids (HPAs) supported on silica, alumina or silica-alumina were used as catalysts. The course of the reaction was found to be very sensitive to the nature of the HPA as well as the support. Solid characterization by Raman spectroscopy, XRD, and pyridine-FTIR revealed that only combinations of tungsten-based HPAs and silica support were able to preserve the structure of active component throughout the preparation process, which was essential to obtain active and selective catalysts. The interaction between HPA and support was decisive for stability and dispersion of the catalytically active species. With the best performing catalyst H4SiW12O40/SiO2, selectivity to triacetin reached 71% at complete conversion within 24?h. The high selectivity to triacetin is attributed the Br?nsted acidic sites originated from stabilized Keggin structure and continuous removal of water during course of reaction. Toluene is able to form azeotropic mixtures with water and acetic acid and keeps the reaction temperature below the boiling point of acetic acid. Thus, water-free reaction conditions can be established. The catalyst was reusable; however, the activity and selectivity towards triacetin slightly decreased in a repetition run due to loss of active sites.
- Kale,Armbruster,Eckelt,Bentrup,Umbarkar,Dongare,Martin
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- Biobased catalyst in biorefinery processes: Sulphonated hydrothermal carbon for glycerol esterification
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Sulphonated hydrothermal carbon (SHTC), obtained from d-glucose by mild hydrothermal carbonisation and subsequent sulphonation with sulphuric acid, is able to catalyse the esterification of glycerol with different carboxylic acids, namely, acetic, butyric and caprylic acids. Product selectivity can be tuned by simply controlling the reaction conditions. On the one hand, SHTC provides one of the best selectivity towards monoacetins described up to now without the need for an excess of glycerol. On the other hand, excellent selectivity towards triacylglycerides (TAG) can be obtained, beyond those described with other solid catalysts, including well-known sulphonic resins. Recovery of the catalyst showed partial deactivation of the solid. The formation of sulphonate esters on the surface, confirmed by solid state NMR, was the cause of this behaviour. Acid treatment of the used catalyst, with subsequent hydrolysis of the surface sulphonate esters, allows SHTC to recover its activity. The higher selectivity towards mono- and triesters and its renewable origin makes SHTC an attractive catalyst in biorefinery processes.
- De La Calle, Carlos,Fraile, José M.,García-Bordejé, Enrique,Pires, Elísabet,Roldán, Laura
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p. 2897 - 2903
(2015/05/13)
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- Heteropolyacid-based ionic liquids as efficient homogeneous catalysts for acetylation of glycerol
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A series of homogeneous catalysts consisting of pyridinium propyl sulfobetaine (PPS), tungstophosphoric acid (TPA), and acetic acid (HOAc) have been synthesized and exploited for catalytic acetylation of glycerol (GL). Their acid properties were characterized by 31P NMR of trimethylphosphine oxide (TMPO) as the probe molecule, and the effects of acidic strength, PPS/TPA, TPA/GL, and HOAc/GL ratios as well as reaction temperature on catalytic performances during acetylation reaction were investigated. These water-tolerable PPS-TPA-HOAc catalysts, which tend to segregate from glycerol acetate products to form distinct biphasic liquid layers spontaneously after the reaction, were found to be highly efficient and durable for acetylation reaction under continuous operation conditions. Typically, a complete GL conversion may be achieved with a superior glycerol triacetate (GTA) selectivity of 86-99%. Moreover, the unique self-separation biphasic characteristics of the catalyst system facilitate facile separation of products and recycling of catalyst, rendering practical industrial applications in acetylation of alcohol.
- Huang, Ming-Yu,Han, Xiao-Xiang,Hung, Chin-Te,Lin, Jann-Chen,Wu, Pei-Hao,Wu, Jung-Chung,Liu, Shang-Bin
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- The synthesis of glycerol carbonate from glycerol and CO2 over La2O2CO3-ZnO catalysts
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The transformation of CO2 and glycerol into glycerol carbonate was carried out by using acetonitrile as coupling agent over La 2O2CO3-ZnO in the present work. A series of La-Zn mixed oxide catalysts with different molar ratios were prepared and calcined at different temperatures. The catalysts were characterized by N 2 physisorption, XRD, XPS, FT-infrared spectroscopy and temperature-programmed desorption of CO2. The results revealed that the formation of La2O2CO3 improved the surface basicity which then favors the CO2 activation and the carbonate yield was shown to be correlated with the amount of moderately basic sites. The XPS measurement demonstrated that La2O2CO3 favored the electron transfer from zinc atoms to lanthanum atoms or oxygen atoms which then favors the activation of glycerol. The synergism between ZnO and La 2O2CO3 is responsible for the high catalytic activities of the La-Zn catalysts. The best result was obtained on the catalyst with molar ratio of La:Zn = 1:4 and calcination at 500 °C.
- Li, Hongguang,Gao, Dengzheng,Gao, Peng,Wang, Feng,Zhao, Ning,Xiao, Fukui,Wei, Wei,Sun, Yuhan
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p. 2801 - 2809
(2013/09/24)
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