Valeric Biofuels: A Platform of Cellulosic Transportation Fuels

Abstract

At the beginning of the 21st century mankind is facing an energy challenge as a consequence of the world s increasing energy demand, the depletion of "easy" oil and gas fields, and the impact of CO 2 emissions on the Earth s climate ("three hard truths"). [1] Much research is therefore being devoted to the exploration and development of new, carbon-lean energy sources. These include biofuels, which are the most promising option for the transportation sector in the coming decades. [2] The first generation of biofuels is presently produced from sugars, starches, and vegetable oil. Although instrumental in developing the market, these biofuels are not likely to deliver the large volumes needed for the transport sector because they directly compete with food for their feedstock. A more promising feedstock is lignocellulosic material, which is more abundant, has a lower cost, and is potentially more sustainable. [3] Lignocellulose is recalcitrant and, therefore, requires complex and expensive processes for upgrading to biofuels. [4] Interestingly, it has been claimed that levulinic acid (LA) can be easily and cheaply produced from lignocellulosic materials by using a simple and robust hydrolysis process. [5] Several LA derivatives have been proposed for fuel applications, for instance ethyl levulinate (EL), g-valerolactone (gVL), and methyl tetrahydrofuran (MTHF). [5,6] However, these components do not exhibit satisfactory properties when blended in current fuels. Herein, we present a new platform of LA derivatives, the "valeric biofuels", which we have been developing since 2004 and which can deliver both gasoline and diesel components that are fully compatible with transportation fuels.The manufacture of valeric biofuels (Scheme 1) consists of the acid hydrolysis of lignocellulosic materials to LA, the hydrogenation of the acid to gVL and valeric acid (VA), and finally esterification to alkyl (mono/di)valerate esters. One of these steps, the hydrogenation of gVL to VA (Scheme 1, step 3), has not been reported in the literature and was developed in our laboratory. All the other steps are known but were nevertheless revisited and, wherever possible, improved. This holds for the acid-catalyzed hydrolysis of lignocellulose to LA, [5,7] the hydrogenation of LA to gVL with the use of supported metal catalysts, [8] as well as the familiar esterification of carboxylic acids. Herein, we present the main results of the hydrogenation of gVL to VA (Scheme 1, step 3), key improvements in the hydrogenation of LA to gVL (step 2), options for integrating steps 2-4, and finally a thorough evaluation of the fuel performance of the resulting

Highly Selective Hydrogenation of Levulinic Acid to γ-Valerolactone Over Ru/ZrO2 Catalysts

“…We must ensure that we hydrogenate only the keto group, enabling the cyclisation to the lactone product. Previous studies have shown that both the size and the dispersion of the ruthenium sites are crucial, as well as the properties of the support [17,21,32,33]. This is because the hydrogenation of keto group is catalysed by a combined effort of both the ruthenium active site and the support.…”

“…The mechanical, thermal and chemical properties of ZrO 2 are favourable for these reactions. It is stable under coking conditions and remains active even after a week's exposure to hot carboxylic acid [21]. Thus, we chose zirconia as support (ZrOH and ZrO 2 ) and prepared Ru/ZrO 2 catalysts using different pre-treatments.…”

“…These include γ-valerolactone (GVL, 2), 1,4-pentanediol, methyltetrahydrofuran, and valeric acid and esters [16,17]. Of these, the stable and non-toxic GVL has already several applications: it can be used directly as a fuel additive or as a precursor for fuels and chemicals and as a renewable solvent [10,[18][19][20][21]. Various companies such as Green Future SRL, DuPont, Segetis and Biofine have developed processes for the manufacturing of levulinic acid through bio-based routes.…”

Do engenho à biorrefinaria: a usina de açúcar como empreendimento industrial para a geração de produtos bioquímicos e biocombustíveis

“…Duas publicações recentes por Bond et al 110 e Lange et al 111 sugerem que o ácido levulínico derivado por desidratação de glicose pode ser intermediário em processos de conversão catalítica para gerar ésteres do ácido valérico. 112 A transformação da γ-valerolactona na presença de Pb/Nb 2 O 6 gera como intermediários alquenos que sofrem posterior oligomerização para formar alcanos C 9 -C 16 com potencial de serem empregados como combustíveis líquidos tipo diesel.…”

The Nature of Surface Deposits Following Valeric Acid Interactions with Al2O3-Supported Alkaline Earth Oxide Catalysts: Towards Cellulosic Biofuels

“…There has been significant recent interest in the use of valeric acid for the production of biodiesel [17 -21] and, in particular the use of the ketonic decarboxylation reaction to form 5-nonanone (see figure 1(b)) [22,23].…”