Biodiesel has shown great promise to supplement the fossil diesel since it is a renewable energy resource and is environmentally friendly. However, the major obstacle to biodiesel large scale commercialization is the high production cost; so converting glycerol, the by-product of a biodiesel process, into value-added products is an efficient way to promote biodiesel production. 1,2-propanediol (1,2PD), also known as propylene glycol, is an important commodity chemical used for many applications such as polyester resins, liquid detergents and anti-freeze. It can be produced via dehydration of glycerol into acetol followed by hydrogenation of acetol into 1,2PD using a bi-functional catalyst. Currently high pressure gaseous hydrogen added for hydrogenation causes safety issues as well as additional costs of hydrogen purchasing, transportation and storage. Therefore, the utilization of the in situ hydrogen produced by steam reforming of a hydrogen carrier could be a novel route for this process. In this work, processes of glycerol hydrogenolysis to produce 1,2PD have been developed using different hydrogen sources, i.e. molecular hydrogen and in situ hydrogen produced by steam reforming. Three different preparation methods were attempted to prepare a Cu/ZnO/Al2O3 catalyst in a glycerol hydrogenolysis process, which were oxalate gel-coprecipitation, Na2CO3 coprecipitation and impregnation. The catalyst prepared by oxalate gel-coprecipitation showed the highest activity for production of 1,2PD. It was also found that the addition of alumina did not only improve the activity but also enhanced the stability of the Cu/ZnO catalyst as shown by the catalyst recycling experiments. The morphological and chemical properties of the catalysts were characterized via XRD, NH3 TPD, TGA and TEM. Compared with other preparation methods, the Cu/ZnO/Al2O3 catalyst prepared by oxalate gel-coprecipitation exhibited a well-mixed form for all the metals as suggested by the XRD and TGA results; the particle size of the Cu/ZnO/Al2O3 catalyst was smaller as shown in the XRD and TEM results, and also based on NH3 TPD analysis the Cu/ZnO/Al2O3 catalyst showed stronger acidic sites. When Ni was loaded onto the Cu/ZnO/Al2O3 catalyst by oxalate gel-coprecipitation, it was found that the activity for acetol hydrogenation was improved but the overall glycerol hydrogenolysis reaction was slower. This was mainly due to the reduced amount of strong acidic sites caused by the addition of Ni as observed from the NH3 TPD results. 2wt% Pd supported on a Cu/MgO/Al2O3 catalyst was used in this process. Higher reaction rate and higher 1,2PD selectivity could be obtained compared with a Cu/ZnO/Al2O3 catalyst. However, a significant deactivation was observed when the spent catalyst was used. The catalyst deactivation was mainly due to catalyst sintering during the reaction resulting in a larger particle size as suggested by XRD results. The activation energies for the glycerol hydrogenolysis reaction using Cu/ZnO/Al2O3 and Pd supported on Cu/MgO/Al2O3 catalysts have been calculated. The activation energy was calculated to be 69.39kJ/mole using a Cu/ZnO/Al2O3 catalyst and 113.62kJ/mol using a Pd supported on Cu/MgO/Al2O3 catalyst. It is suggested that the reaction was chemically kinetically controlled using both catalysts and the reaction using the Pd supported on Cu/MgO/Al2O3 catalyst was more temperature dependent. It was found that the 1,2PD selectivity was strongly dependent on hydrogen pressure. The low 1,2PD selectivity at lower hydrogen pressure was due to the formation of by-products caused by side reactions with acetol. The kinetic data of acetol hydrogenation suggested that the acetol hydrogenation step was significantly faster than the overall reaction and hence the glycerol dehydration step was the rate-determining-step. In the glycerol hydrogenolysis process using in situ hydrogen, the activities of the Cu/ZnO/Al2O3 catalysts prepared by different methods were determined and the experimental results show that the catalyst prepared by oxalate gel-coprecipitation has the best catalytic activity for glycerol conversion and 1,2PD selectivity. With Ni loaded onto a Cu/ZnO/Al2O3 catalyst, the 1,2PD selectivity was improved and the glycerol conversion was lower. It might be because Ni could improve the steam reforming activity to produce more hydrogen, but due to the reduced strong acidic sites based on the NH3 TPD results glycerol conversion was decreased. Cu/MgO/Al2O3 catalysts prepared by oxalate gel-coprecipitation were used in this process and the activity was found to be higher, i.e. higher glycerol conversion and 1,2PD selectivity, compared with the Cu/ZnO/Al2O3 catalyst due to a higher amount of acidic sites based on the NH3 TPD results; the Cu/Mg/Al composition was optimized. When Ni was added into a Cu/MgO/Al2O3 catalyst, it was found that with only 1mole% Ni loaded, the glycerol conversion was lower than that without Ni loaded and the 1,2PD selectivity was slightly improved; when the Ni loading was increased to 5mole%, the catalyst was almost completely inactive, since when 5mole% Ni was loaded, the acidic sites were almost completely eliminated as observed from the NH3 TPD results. When Pd was added onto a Cu/MgO/Al2O3 catalyst the 1,2PD selectivity was significantly improved. When Pd was loaded, more surface hydrogen atoms were provided as observed from the H2 TPD results. Cu/ZnO/Al2O3 and Cu/MgO/Al2O3 catalysts have been recycled and reused to investigate the stability of the catalysts. All the catalysts were deactivated after they were recycled and reused, since it was apparent that catalyst sintering occurred during the reaction resulting in a larger particle size based on the XRD results. The deactivation of the spent catalyst was also possibly due to the formation of carbonate when the metals were contacted with CO2 which was formed via steam reforming.

Due to its availability, low-price, and higher degree of reduction than lignocellulosic sugars, glycerol has become an attractive carbon source for the production of fuels and reduced chemicals. However, this high degree of reduction of carbon atoms in glycerol also results in significant challenges in regard to its utilization under fermentative conditions. Therefore, in order to unlock the full potential of microorganisms for the fermentative conversion of glycerol into fuels and chemicals, a detailed understanding of the anaerobic fermentation of glycerol is required. The work presented here highlights a comprehensive experimental investigation into fermentative glycerol metabolism in Escherichia coli, which has elucidated several key pathways and mechanisms. The activity of both the fermentative and respiratory glycerol dissimilation pathways was found to be important for maximum glycerol utilization, a consequence of the metabolic cycle and downstream effects created by the essential involvement of PEP-dependent dihydroxyacetone kinase (DHAK) in the fermentative glycerol dissimilation pathway. The decoupling of this cycle is of central importance during fermentative glycerol metabolism, and while multiple decoupling mechanisms were identified, their relative inefficiencies dictated not only their level of involvement, but also implicated the activity of other pathways/enzymes, including fumarate reductase and pyruvate kinase. The central role of the PEP-dependent DHAK, an enzyme whose transcription was found to be regulated by the cyclic adenosine monophosphate (cAMP) receptor protein (CRP)-cAMP complex, was also tied to the importance of multiple fructose 1,6-bisphosphotases (FBPases) encoded by fbp, glpX, and yggF. The activity of these FBPases, and as a result the levels of fructose 1,6-bisphosphate, a key regulatory compound, appear to also play a role in the involvement of several other enzymes during fermentative glycerol metabolism including PEP carboxykinase. Using this improved understanding of fermentative glycerol metabolism as a platform, E. coli has been engineered to produce high yields and titers of ethanol (19.8 g/L, 0.46 g/g), co-produced along with hydrogen, and 1,2-propanediol (5.6 g/L, 0.21 g/g) from glycerol, demonstrating its potential as a carbon source for the production of fuels and reduced chemicals.

O presente trabalho teve como objetivo avaliar o efeito de aditivos químicos, microbianos e a associação destes sobre a dinâmica fermentativa e a estabilidade aeróbia de silagens de cana-de-açúcar, além de avaliar o desempenho de vacas leiteiras de alto potencial produtivo recebendo rações com diferentes fontes de volumosos. No primeiro experimento silagens de cana-de-açúcar foram confeccionadas em silos laboratoriais de 20L, contendo válvula para escape de gases e coleta de efluente. O experimento seguiu o delineamento inteiramente ao acaso, em esquema fatorial sendo constituído por dois períodos de abertura (80 e 140 dias) com 8 tratamentos e 4 repetições. Os tratamentos avaliados foram: uréia 1%MV, 1,2- propanodiol 1%MS (1,2 p), L. L. buchneri 5x104 ufc/g (Lb), L. diolivorans em duas concentrações 1x105 ufc/g (Ld 105 e 1x10 6 ufc/g (Ld 106), L. diolivorans 1x106 ufc/g + L.buchneri 5x104 ufc/g (Ld+Lb) e 1,2-propanodiol 1%MS + L. diolivorans 1x 106 ufc/g (1,2 p+Ld 106). Após abertos os silos foram realizadas avaliações de estabilidade aeróbia em sala com ambiente controlado. Os tratamentos contendo L. diolivorans mais 1,2- propanodiol ou L. diolivorans mais L. buchneri apresentaram os menores valores de perda total de matéria seca 20,42% e 23,73%, respectivamente. Ambos tratamentos também resultaram nos menores teores de etanol, 2,1% e 3,93% da MS, e de perdas gasosas, 20,36% e 20,62%. Tanto para FDN quanto FDA, foram observados valores menores para os tratamentos contendo uréia, 1,2-p + Ld 106 Ld + Lb e Ld 105. Quanto à estabilidade aeróbia houve diferenças entre os períodos de abertura, sendo de 48,03h aos 140 dias e de 31,35h aos 80 dias. O microrganismo L. diolivorans se constituiu em uma alternativa capaz de trazer benefícios quanto às perdas fermentativas e composição bromatológica em silagens de cana-de-açúcar. O segundo experimento avaliou o desempenho de vacas recebendo rações contendo diferentes fontes de volumosos: cana-de-açúcar in natura, silagem de cana-de-açúcar inoculada com L. buchneri silagem de milho e proporções equivalentes de silagem de milho e cana-deaçúcar in natura (50:50). O experimento contou com 48 vacas Holandesas em estágio intermediário de lactação, distribuídas em múltiplos quadrados latinos 4x4 com períodos de 21 dias, sendo 14 dias de adaptação e 7 dias de coleta de amostras. Além da avaliação de desempenho, foram realizadas análises de composição bromatológica dos alimentos e do leite, e avaliações do comportamento ingestivo dos animais e da estabilidade aeróbia dos volumosos e das rações. Os dados de desempenho mostraram diferenças na ingestão de MS, com maiores valores observados para o tratamento silagem de cana-de-açúcar (23,5 kg/dia) e a mistura cana-de-açúcar mais silagem de milho (23,5 kg/dia). Todas as rações resultaram em produções elevadas de leite (22,65 kg/dia) as quais não diferiram entre si. A composição do leite variou somente para o teor de gordura, sendo maior para a silagem de milho (3,61%) e a mistura com cana (3,48%). A silagem de cana-de-açúcar mostrou-se como alternativa interessante frente à cana-de-açúcar in natura, e que ambas podem proporcionar elevadas produções desde que as rações sejam corretamente balanceadas. / The current study aimed to evaluate the effect of chemical and microbial additives and the combination over the fermentative dynamics and the aerobic stability in the sugarcane silage as well to study the performance of high producing dairy cows fed with different roughage sources. In the first trial, sugarcane silage was prepared in lab silos of 20L, with a gas relief valve and a device for collecting effluent. The experiment was randomly arranged, in a factorial design, with two openings 80 and 140 days, across 8 treatments and 4 replications. The treatments evaluated were: urea 1%, 1.2-propanediol 1%DM (1.2 p) L. buchneri 5x104 cfu/g (Lb), L. diolivorans in two concentrations 1x105 cfu/g (Ld 105) and 1x106 cfu/g (Ld 106), L. diolivorans 1x106 cfu/g plus L. buchneri 5x104 cfu/g (Ld+Lb) and 1.2- propanediol 1%DM plus L. diolivorans 1x 106 cfu/g (1,2 p+Ld 106). After opening the silos, the aerobic stability assay was performed in an environmental controlled room. The treatments containing Ld +1.2 p, or Ld 106 + Lb showed the lowest values of total DM loss, 20.42% and 23.73% respectively. Both treatments also showed the lowest levels of ethanol 2.1% and 3.93% of DM, and gases losses 20.36% and 20.62%. For both NDF and ADF, lower values were detected for the following treatments: urea, 1.2 p + Ld 106, Ld + Lb and Ld105. As for the aerobic stability, there were differences between the openings dates, 48.03h (140 days) and 31.35h (80 days). The microorganism L. diolivorans turn out to be promising alternative able to show positive results on the fermentative losses and nutritive value in sugarcane silage. The second experiment evaluated the performance of cows fed rations with different sources of roughage: fresh sugarcane, sugarcane silage, corn silage and mixture of corn silage and fresh sugarcane (50:50). Forty eight mid lactation Holstein cows were assigned to multiple latin square design 4x4, with 21-d period (14-d adaptation and 7-d the sample collection). As well the animal performance fed and milk compositions were evaluated and also ingestivo behavior of cows and the aerobic stability of forage and rations were analyzed. The performance data has shown differences in the dry matter intake (DMI), with the highest values observed for the sugarcane silage (23.5 kg/day) and the mixture (23.5 kg/day). All rations resulted in high milk production (22.65 kg/day) which did not differ among treatments. The milk composition varied only for the fat percentage, which was higher for the corn silage treatment (3.61%) and the mix (3.48%). Sugarcane silage was exhibited as an interesting forage alternative when compared to fresh sugarcane. Both options may support high milk yields by the adequacy of rations balancing.

O presente trabalho teve como objetivo avaliar o efeito de aditivos químicos, microbianos e a associação destes sobre a dinâmica fermentativa e a estabilidade aeróbia de silagens de cana-de-açúcar, além de avaliar o desempenho de vacas leiteiras de alto potencial produtivo recebendo rações com diferentes fontes de volumosos. No primeiro experimento silagens de cana-de-açúcar foram confeccionadas em silos laboratoriais de 20L, contendo válvula para escape de gases e coleta de efluente. O experimento seguiu o delineamento inteiramente ao acaso, em esquema fatorial sendo constituído por dois períodos de abertura (80 e 140 dias) com 8 tratamentos e 4 repetições. Os tratamentos avaliados foram: uréia 1%MV, 1,2- propanodiol 1%MS (1,2 p), L. L. buchneri 5x104 ufc/g (Lb), L. diolivorans em duas concentrações 1x105 ufc/g (Ld 105 e 1x10 6 ufc/g (Ld 106), L. diolivorans 1x106 ufc/g + L.buchneri 5x104 ufc/g (Ld+Lb) e 1,2-propanodiol 1%MS + L. diolivorans 1x 106 ufc/g (1,2 p+Ld 106). Após abertos os silos foram realizadas avaliações de estabilidade aeróbia em sala com ambiente controlado. Os tratamentos contendo L. diolivorans mais 1,2- propanodiol ou L. diolivorans mais L. buchneri apresentaram os menores valores de perda total de matéria seca 20,42% e 23,73%, respectivamente. Ambos tratamentos também resultaram nos menores teores de etanol, 2,1% e 3,93% da MS, e de perdas gasosas, 20,36% e 20,62%. Tanto para FDN quanto FDA, foram observados valores menores para os tratamentos contendo uréia, 1,2-p + Ld 106 Ld + Lb e Ld 105. Quanto à estabilidade aeróbia houve diferenças entre os períodos de abertura, sendo de 48,03h aos 140 dias e de 31,35h aos 80 dias. O microrganismo L. diolivorans se constituiu em uma alternativa capaz de trazer benefícios quanto às perdas fermentativas e composição bromatológica em silagens de cana-de-açúcar. O segundo experimento avaliou o desempenho de vacas recebendo rações contendo diferentes fontes de volumosos: cana-de-açúcar in natura, silagem de cana-de-açúcar inoculada com L. buchneri silagem de milho e proporções equivalentes de silagem de milho e cana-deaçúcar in natura (50:50). O experimento contou com 48 vacas Holandesas em estágio intermediário de lactação, distribuídas em múltiplos quadrados latinos 4x4 com períodos de 21 dias, sendo 14 dias de adaptação e 7 dias de coleta de amostras. Além da avaliação de desempenho, foram realizadas análises de composição bromatológica dos alimentos e do leite, e avaliações do comportamento ingestivo dos animais e da estabilidade aeróbia dos volumosos e das rações. Os dados de desempenho mostraram diferenças na ingestão de MS, com maiores valores observados para o tratamento silagem de cana-de-açúcar (23,5 kg/dia) e a mistura cana-de-açúcar mais silagem de milho (23,5 kg/dia). Todas as rações resultaram em produções elevadas de leite (22,65 kg/dia) as quais não diferiram entre si. A composição do leite variou somente para o teor de gordura, sendo maior para a silagem de milho (3,61%) e a mistura com cana (3,48%). A silagem de cana-de-açúcar mostrou-se como alternativa interessante frente à cana-de-açúcar in natura, e que ambas podem proporcionar elevadas produções desde que as rações sejam corretamente balanceadas. / The current study aimed to evaluate the effect of chemical and microbial additives and the combination over the fermentative dynamics and the aerobic stability in the sugarcane silage as well to study the performance of high producing dairy cows fed with different roughage sources. In the first trial, sugarcane silage was prepared in lab silos of 20L, with a gas relief valve and a device for collecting effluent. The experiment was randomly arranged, in a factorial design, with two openings 80 and 140 days, across 8 treatments and 4 replications. The treatments evaluated were: urea 1%, 1.2-propanediol 1%DM (1.2 p) L. buchneri 5x104 cfu/g (Lb), L. diolivorans in two concentrations 1x105 cfu/g (Ld 105) and 1x106 cfu/g (Ld 106), L. diolivorans 1x106 cfu/g plus L. buchneri 5x104 cfu/g (Ld+Lb) and 1.2- propanediol 1%DM plus L. diolivorans 1x 106 cfu/g (1,2 p+Ld 106). After opening the silos, the aerobic stability assay was performed in an environmental controlled room. The treatments containing Ld +1.2 p, or Ld 106 + Lb showed the lowest values of total DM loss, 20.42% and 23.73% respectively. Both treatments also showed the lowest levels of ethanol 2.1% and 3.93% of DM, and gases losses 20.36% and 20.62%. For both NDF and ADF, lower values were detected for the following treatments: urea, 1.2 p + Ld 106, Ld + Lb and Ld105. As for the aerobic stability, there were differences between the openings dates, 48.03h (140 days) and 31.35h (80 days). The microorganism L. diolivorans turn out to be promising alternative able to show positive results on the fermentative losses and nutritive value in sugarcane silage. The second experiment evaluated the performance of cows fed rations with different sources of roughage: fresh sugarcane, sugarcane silage, corn silage and mixture of corn silage and fresh sugarcane (50:50). Forty eight mid lactation Holstein cows were assigned to multiple latin square design 4x4, with 21-d period (14-d adaptation and 7-d the sample collection). As well the animal performance fed and milk compositions were evaluated and also ingestivo behavior of cows and the aerobic stability of forage and rations were analyzed. The performance data has shown differences in the dry matter intake (DMI), with the highest values observed for the sugarcane silage (23.5 kg/day) and the mixture (23.5 kg/day). All rations resulted in high milk production (22.65 kg/day) which did not differ among treatments. The milk composition varied only for the fat percentage, which was higher for the corn silage treatment (3.61%) and the mix (3.48%). Sugarcane silage was exhibited as an interesting forage alternative when compared to fresh sugarcane. Both options may support high milk yields by the adequacy of rations balancing.