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Concept and objectives:
The concept of the project
The project “Hydrogen production from hydroxylic compounds resulted as biomass processing wastes” is proposed to Joint Applied Research Projects Competition for Domain 2: Energy Research direction 2.1.4. The project application fits in the above mentioned domain and direction because it proposes the energetic valorization of waste glycerol obtained in biodiesel fabrication by its transformation in hydrogen – a very promising energy vector. This alternative for hydrogen production contributes to the reduction of CO2 emissions, because it does not bring supplementary CO2 in the environment: the produced CO2 is only that initially consumed by plants to grow.
Demand for hydrogen (H2) will grow up in the next decades due to the technological advancements in fuel cell industry which permit its transformation in electricity and heat without generating polluting gases. On Earth shell, virtually, it does not exist as hydrogen molecule: it is associated with oxygen in water, with carbon in fossil hydrocarbons and both with oxygen and carbon in bioresources (carbohydrates, cellulosic and lignocellulosic matter, lignin, etc). At present, almost 95% of the world’s hydrogen is being produced from fossil fuel based feedstock. The process is economically viable, but it has two major drawbacks:
(i) the diminution of fossil fuel reserves. According to some recent reports [1,2], if the annual consumption of fossil fuels will be maintained at the same level, the oil reserves will be finished in approximately 50 years and natural gases in 65 years;
(ii) steam reforming is not a green process on an environmental point of view, since all (or almost all) of the carbon from hydrocarbons is transformed into carbon dioxide and released in the environment.
In these conditions, one alternative is to replace fossil fuels by biofuels as raw materials for hydrogen production. Biomass is renewable and, although carbon dioxide is still produced, it may be recycled to new biomolecules by photosynthesis, resulting a carbon neutral cycle. If the raw materials for hydrogen production are wastes or are produced by wastes, the overall benefits of the hydrogen production method are even higher.
In this project we propose a laboratory scale technology to produce hydrogen from glycerol wastes resulted in biodiesel fabrication. In the process of biodiesel fabrication by transesterification of vegetable oils with methanol, glycerol is generated at a rate of 1 mol at every 3 mol of methyl esters; approximately 10 wt.% of the total product. Over the last few years the demand and production of biodiesel has increased tremendously and therefore large amounts of glycerol (1.5 million tons per year predicted for 2012 in EU and USA) are available at very low prices [3]. At present, glycerol is just in excess but in the near future it could become a waste problem. It may create a barrier for the development of this industry branch and reduce biodiesel applications as well. Although glycerol is a versatile product, the main problem in the way of a possible usage of the waste glycerol solutions is their composition: water, glycerol, methanol, free fatty acids, methyl esters, unreacted mono-, di- and triglycerides, a variety of other organic molecules in low concentrations, plus inorganic salts remained from the catalysts used in transesterification. As such, crude glycerol, with an approximately 50 % concentration of glycerol, has no direct uses and its value is very low. The purification of crude glycerol is very expensive and is not economically viable. The main scientific and technologic barrier which will be approached in this project is the possible usage of crude glycerol solutions for hydrogen production. One of the advantages of using these wastes for hydrogen production is that only a partial purification of these wastes is needed. Most of the oxygenated molecules contained in crude glycerol can be theoretically implied in steam reforming reaction in parallel with glycerol, being transformed in hydrogen. This is the reason for which in our approach of this project we will first study the catalytic steam reforming of primary alcohols (methanol being the second product after glycerol in crude glycerol solutions). We will focus our studies on steam reforming of ethanol and not methanol due to two reasons: (i) the structure of these two alcohols being similar, the catalysts and the reaction conditions for steam reforming should be similar; (ii) following the catalytic and technological studies, a technology for hydrogen production from crude bioethanol obtained from wood waste can be developed, increasing in this way the value of project results.
The bioethanol will be produced by P2 ICIA by fermentation of wood wastes. Crude glycerol solutions will be provided by P3 REVIVA, analyzed and partially purified in collaboration with P2 ICIA.
The chemical process by which the hydroxylic compounds are transformed in hydrogen is catalytic steam reforming (performed by CO INCDTIM). The main reaction which takes place for glycerol steam reforming (GlySR) is:
OH-CH2-CH(OH)-CH2-OH + 3H2O → 3CO2 + 7H2 (1)
Practically, beside these reactions a series of other reactions take place simultaneously, involving:
(i) partially C-C bond breaking resulting in alkanes, alkenes, C1-C2 alcohols;
(ii) partially oxidation of OH groups, resulting aldehydes, acids;
(iii) partially oxidation of the carbon resulted in a mixture of carbon oxides in the effluent gases;
(iv) carbon deposition as inert graphite on the catalysts surface followed by catalysts deactivation.
The result is a decrease of hydrogen production combined with an increase of separation and purification effort. A good selection of catalysts and reaction conditions will diminish the side reactions and will favor the main reaction (1) with results in overall hydrogen production.
For ethanol steam reforming (EtSR) the main reaction is:
C2H5OH + H2O → CO2 + H2O (2)
The catalytic experiments will be performed at a scale of 1g of catalyst and the following will be determined: the catalytic activity, the selectivity for hydrogen production, the catalysts life time, and the reaction conditions. After the reforming process, the resulting gaseous products will enter in a separation unit based on a Pd membrane filter to finally obtain purified hydrogen. A set of experimental data will be provided containing the conditions for which the explored parameters have the optimum values. These data will be further used by P1 UBB to model and design a catalytic technology at one order of magnitude higher level (tens of grams of catalyst).
The scheme of the catalytic technology proposed by this project is presented in Figure 1.
Figure 1. Catalytic production of hydrogen from bioethanol and glycerol.
A laboratory scale experimental set-up will be designed and realized on which the catalytic technology will be tested. The main parts of this experimental set-up are: the evaporator, the catalytic reactor and the hydrogen separator. This set-up will be designed by P4 ROKURA and realized in collaboration with CO INCDTIM. Technological tests and technology developments will be realized by CO INCDTIM in collaboration with P4 ROKURA.
The project objectives
The main objective of this project proposal is to develop a laboratory scale technology and experimental set-up to produce hydrogen by steam reforming of hydroxylic compounds (monohydroxylic alcohols and glycerol) resulted as wastes in biomass processing or prepared from wastes of biomass.
Besides this main objective, the project has 7 specific objectives. The objective description, followed by the novelty and original results expected from each objective, is presented below:
O1. Preparation and structural characterization of oxide supported nickel catalysts additivated with noble metals and/or rare earth oxides.
- the catalysts which are intended to be prepared are mixed catalysts based on Ni/oxide. Nickel was chosen for its well known efficiency in hydrocarbon steam reforming reactions. We propose the addition of noble metals and/or rare earth oxides to improve the selectivity and stability properties.
- the project proposes catalysts preparation using both classic methods (impregnation) and new techniques (sol-gel). New catalysts will be prepared using combinations of noble metals and rare earth oxides which have not been reported before.
- a complete and accurate catalysts characterization is crucial in heterogeneous catalysis in order to obtain reproducible results. We propose in this project a set of physico-chemical methods which will provide a complete structural, morphological and surface characterization of prepared catalysts.
O2. Preparation, determination of the chemical composition and possibilities of partial purification of crude alcohols and crude glycerol solutions.
- bioethanol is prepared by fermentation of waste wood; a new method will be proposed to produce crude bioethanol suitable to be used with minimum purification effort for catalytic steam reforming;
- waste glycerol solutions result in biodiesel production process; a purification method will be proposed to transform these wastes in raw materials for catalytic steam reforming.
O3. Proposal and evaluation from conceptual design and from technical and environmental impact perspectives the hydrogen production by steam reforming of hydroxylic compounds (monohydroxylic alcohols and glycerol).
- the project proposes to develop a detailed and advanced mathematical model for the hydrogen production process based on catalytic steam reforming of hydroxylic compounds, simulation of the mathematical model, characterization of the system behavior based on simulation results;
- the validation of the models will be made using experimental data followed by scale-up analysis, sensitivity analysis and technology development;
- Based on experimental and simulation results, a techno-economical evaluation and environmental impact assessment of hydrogen production based on catalytic steam reforming processes of biomass processing wastes will be performed.
O4. Technological studies of ethanol and glycerol catalytic steam reforming on Ni based catalysts, additivated with noble metals and/or rare earth oxides.
- Catalytic studies of ethanol and glycerol catalytic steam reforming will be performed in order to establish the optimum catalyst – reaction conditions system;
- A special attention will be paid to catalysts stability studies (catalysts life-time, deactivation mechanism, possibilities of regeneration), very modern techniques being used in this purpose: Thermogravimetry (TGA), Thermo Programmed Oxidation (TPO), Transmission Electron Microscopy (TEM).
O5. Design, fabrication and testing of a laboratory scale experimental set-up to produce hydrogen from waste glycerol solutions.
- this objective implies: the design an fabrication of the evaporator and catalytic reactor, measurement and control of temperatures and flows, on-line analysis of effluent gases.
O6. Dissemination activities: papers, presentations at international conferences, web page, elaboration of one PhD thesis, patent application.
O7. Project management activities.
The original, novelty and innovative nature of the project
The original and innovative nature of this project proposal is based on its strong interdisciplinary character which:
(i) combines in a coherent manner knowledge from various fields: chemistry, heterogeneous catalysis, kinetic analysis, chemical reaction engineering, experimental optimization, thermo-energy conversion processes, process design and integration, computational techniques (modeling and simulation of complex systems);
(ii) connects the fundamental and applicative research from National Institutes (CO and P2) and Universities (P1) with research developed by economical entities (P3) and by end-users of developed technology (P4).
The project proposes new approaches of some very actual issues like: economically and environmental friendly hydrogen production, wastes management, elaboration of advanced technological models, techno-economical and environmental impact assessment of hydrogen production from glycerol waste.
Expected results and the project end products
The main end product of this project proposal is the experimental set-up and catalytic technology for hydrogen production from waste glycerol correlated with techno-economical and environmental impact assessments. In the project implementation we expect to obtain the following results:
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method for glycerol waste purification by alkaline metals;
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method for preparation of mixed catalysts based on alumina supported nickel;
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evaluation by modeling and simulation of bioethanol steam reforming processes for hydrogen production;
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experimental model for catalysts testing in ethanol and glycerol steam reforming;
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evaluation by modeling and simulation of glycerol steam reforming processes for hydrogen production;
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integrating of young PhD students in the research methodology with impact in the development of their research capacity and potential;
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development of research infrastructure of partners;
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6 ISI papers, 1 patent application, 10 presentations at international conferences;
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1 PhD thesis.
1.2. State of the art:
The state of the art on the subject of the project
Importance of energy issue and efficient utilization of energy reserves in the actual context of human society development are problems that cannot be ignored. The relevance of energy topic must be considered from two important points of view: (i) the first is linked with security of primary energy supplies in term of quantity and competitive prices and (ii) the second one is linked with the necessity of environmental protection and climate change mitigation by reduction of greenhouse gas emissions. The importance of energy theme and its connections with environmental pollution lead to the inclusion of this issue within EU 2020 strategy (EU climate and energy package) and “Resource Efficient Europe” initiative for competitive, sustainable and secure energy (Europe 2020 strategy, 2010). As ways to support research and innovation in energy and environmental areas, various instruments have been put in place. For instance, thematic areas regarding the energy chapter, covered by 7-th Framework Programme include: hydrogen production and fuel cells, fuels and electricity generation from renewable sources, renewable heating and cooling sources, promotion of carbon capture and storage technologies, clean coal technologies, etc.
The development of technologies for the production of carbohydrates, valuable chemicals, biofuels and heat and/or electricity from woody biomass received a special attention in the last years [4]. Ethanol can be produced from various cellulosic materials. One of the most promising technologies in terms of second generation biofuels is lingo-cellulosic treatment underlying to obtain cellulosic bioethanol that is not directly linked to food production. Wood waste is an abundant feedstock in Romania and can be used to produce bioethanol through hydrolysis and fermentation. Bioethanol can be produced from cellulose and hemicellulose [5]. Over the last years, a wide variety of methods for pretreatment, hydrolysis and fermentation have been employed, but each of them presents advantages and disadvantages [6]. In the present, there are pilot or demonstrative plants for bioethanol preparation from cellulose in Sweden, Australia, SUA, Denmark, Spain, Germany and Canada.
Biodiesel, an alternative diesel fuel, is made from renewable biological sources such as vegetable oils and animal fats. Considerable research has been done on vegetable oils as raw materials for biofuels fabrication [7]. This research included palm oil, soybean oil, sunflower oil, coconut oil, rapeseed oil and tung oil. Vegetable oils are transformed in biofuels by transesterification with an alcohol, to form esters and glycerol. Common alcohols used in this process are short chain alcohols, most notably methanol. A catalyst is usually used to improve the reaction rate and yield. After transesterification of triglycerides, the products are a mixture of esters, glycerol, alcohol, catalyst and tri-, di- and monoglycerides. Several chemical [8] and enzymatic [9] processes to produce biofuel from vegetables oils are commercially available. As already mentioned in the previous section, glycerol results as waste in this process; large amounts (1.5 million tons per year predicted for 2012 in EU and USA) are available on the market and its value is very low [3]. The overall profitability of biodiesel production is dependent on the possibility to add value to this by-product.
In the last ten years, many researches have been devoted to the possibility of hydrogen production from bioethanol [10] and glycerol [11]. Alcohols are raw materials well-adapted to the production of hydrogen through catalytic reforming processes due to the fact that they are reactive molecules whose decomposition over catalyst surfaces is much faster than hydrocarbons.
From the noble metals used for ethanol steam reforming, Rh was recognized to be very active and was one of the first studied catalysts [12,13]. Its activity depends on the support nature and catalyst precursor. Other noble metals studied for ethanol steam reforming were: Pt [14], Pd [15] and Ir [16]. Although noble metals are active and selective for hydrogen production, they are very expensive, so many studies were focused on nickel catalysts supported on various oxides: Al2O3, SiO2, MgO, MgAl2O4, La2O3, ZnO, CeO2, CeO2–ZrO2, CexTi1-xO2 or perovskite-type oxides (LaAlO3, SrTiO3 and BaTiO3) [10]. The major problem to overcome with nickel catalysts is to avoid the catalyst deactivation due to metal particle sintering and to coke deposition. To improve the stability of the nickel catalyst, one way is to modify the nature of the support. The best performances were obtained with the more basic supports favoring the ethanol dehydrogenation and inhibiting ethanol dehydration leading to ethylene, which is coke precursor [10]. Another way of improving the stability of Ni-based catalysts consists of adding small amounts of noble metals such as platinum [17] or palladium [18]. The addition of promoters caused a decrease in the NiO reduction temperature. Moreover, the bimetallic catalysts showed a higher ethanol conversion and higher hydrogen yield than the monometallic one, whatever the nature and concentration of the noble metal.
Until now, crude bioethanol has been very rarely used as ethanol source for EtSR reaction. There are few literature reports: the SR of crude bioethanol obtained by fermentation of high starch feed wheat [19], from sugar cane [20] and from wheat straw [21]. Whatever the origin of the bioethanol, a deactivation of the catalyst was observed during the steam reforming reaction that was attributed to the formation of carbon deposits.
Hydrogen can be produced from glycerol via steam reforming [22], partial oxidation (gasification) [23], autothermal reforming [24] and aqueous-phase reforming (APR) [25] processes. If the goal is to produce hydrogen and not synthesis gas, steam reforming is preferred due to the advantage of cumulating in the reaction products hydrogen from both reagents: glycerol and water.
A series of metals were tested in glycerol steam reforming process over ceria-supported catalysts [26]. Ir/CeO2 catalyst was more active for complete glycerol conversion than Co/CeO2 and Ni/CeO2. Ruthenium supported on Y2O3 showed good results in glycerol complete conversion at 600°C and H2 selectivity of 90% [27]. Commercial Ni-based reforming catalysts were also used for H2 production from glycerol [28]. Studies on several Ni catalysts supported on different oxides show that Ni/CeO2 was the best performing catalyst compared to Ni/MgO and Ni/TiO2 under the experimental conditions investigated [29]. Navarro and co-workers [30] have performed steam reforming of glycerol over Ni catalysts supported on alumina with various promoters such as Ce, Mg, Zr and La. Their study concluded that the use of Mg, Zr, Ce and La increases the hydrogen selectivity. Higher activities of those catalysts were attributed to higher Ni concentration, higher stability and higher capacity to activate steam. Several noble metal based catalysts have been studied and it was found that Rh/CeO2/Al2O3 was the best performing catalyst in terms of H2 selectivity and glycerol conversion under the experimental conditions investigated [31].
The number of studies which reported hydrogen production from crude glycerol is much lower [32,33].
Compare the product and technology that you aim to develop with existing products and technologies available worldwide. Analyze how the product and technology that you aim to develop distinguishes from existing product/technology/services which are already patented and/or exploited commercially, in Romania or other countries
The laboratory scale technology proposed by this project addresses a very actual topic which is not exploited yet on large scale. Although the declared objective of most published studies of glycerol steam reforming was to produce hydrogen from crude glycerol, very few were focused on this. In these studies the catalysts are noble metals and the main problem is the presence of impurities in crude glycerol which (i) impeded the performance of the catalyst and (ii) cause a severe catalyst deactivation. Our technology proposes two approaches to overcome these problems: (1) to establish an economically viable method to partially purify the crude glycerol and (2) to test and find new catalysts based on Ni with better activity and resistance to deactivation.
In Romania there is no commercially exploited technology to produce hydrogen from crude glycerol. Although there are a number of international patents [34, 35] for hydrogen production from glycerol, we found no information about a commercially available technology to produce hydrogen from crude glycerol.
Show any contribution by the partners to the state of the art. Show any preliminary results
The team proposed for this project by P1 UBB has internationally recognized results in mathematical modeling and simulation of chemical and thermo-chemical processes [36], modeling of hydrogen production [37], renewable energy sources and energy conversion processes [38].
Partner P2 ICIA has a significant number of results, nationally and internationally acknowledged, regarding biofuels such as: biodiesel, bioethanol and biogas, results materialized in the development of technologies and equipment production. Partner P2 has elaborated and achieved at laboratory scale three technologies for bioethanol production from wood waste, based on three hydrolysis types: (Patent: “Technology for obtaining bioethanol from lignocellulosic biomass (wood waste)”). Wood waste pretreatment reported in literature has almost exclusively focused on chemical pretreatments. ICIA has an important contribution in the development of an eco-friendly pretreatment method that uses only water as solvent to separate the wood waste. Partner P2 ICIA developed in collaboration with P3 REVIVA an original technology for biodiesel production from crude and used vegetable oils (Patent “Biofuel production technology from crude vegetable oil resulted as secondary products in manufacturing of texture soy protein - BIOVALP”).
CO INCDTIM has experience and internationally recognized results in hydrogen involving heterogeneous catalytic processes: hydrogen production from methane, hydrogen storage, H/D isotopic exchange. The team involved in this project developed an original method to study the hydrogen spillover phenomena on the metal/oxide catalysts surface [39] contributing to a better characterization of these types of catalysts. In the last three years the interest was focused in hydrogen production by methane steam reforming using additivated Ni catalysts similar with those proposed in this project. The results show that the addition of Au to Ni and cerium oxide to alumina improves the methane conversion and catalyst stability. The results were published in internationally recognized journals [40, 41] and presented to international conferences.
The results published or patented by all members of the consortium in the area proposed in this project show that they contributed with significant results to the development of these domains.
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