Catalysis for chemicals production from bio-based building blocks: examples of industrial relevance

The research work presented in this PhD thesis is focused on two research topics which aim is to enhance the sustainability of the modern biorefinery. In fact, the production of an advanced biofuel such as 1-butanol is studied in the first part, while the second part deals with the valorisation of glycerol, which is a biodiesel co-product. Therefore, in the first part of the thesis 1-butanol production by means of the Guerbet reaction is studied. The catalytic synthesis of 1-butanol is more desirable than ABE fermentation because it allows to reach higher productivity, lowering the separation costs. The study is aimed to provide a deeper understanding on the effect of acid and base active sites. Therefore, pure basic alkaline earth metal oxides were synthesized and fully characterized. Afterwards, the oxide which showed the best performance was doped with H3PO4 and its catalytic behaviour was studied. Finally, its performance was compared with that one of hydroxyapatite, even with respect to its lifetime. Dihydroxyacetone, a glycerol derivative, upgrading into lactic acid is the topic of the second part of this work. Glycerol valorisation into chemicals might help to support the economic sustainability of biodiesel production. In fact, its disposal as a waste is expensive and not sustainable according to the biorefinery concept. Therefore, a continuous process aimed at directly upgrading glycerol is highly desirable. The main problem in dihydroxyacetone conversion is the need for water-resistant catalysts. A continuous process is more convenient from both an economical and a technological point of view than a batch one. In this thesis, a thorough study of metal phosphate-based catalysts reactivity in the aqueous phase and in a continuous-feed reactor is presented. The catalysts were fully characterized in order to understand the relationship between their physico-chemical characteristics and catalytic performance

A strategy for the measurement of CO2 distribution in the stratosphere

Abstract. In this study we introduce a new strategy for the measurement of CO2 distribution in the stratosphere. The proposed experiment is based on an orbiting limb sounder that measures the atmospheric emission within both the thermal infrared (TIR) and far-infrared (FIR) regions. The idea is to exploit the contribution of the pure rotational transitions of molecular oxygen in the FIR to determine the atmospheric fields of temperature and pressure that are necessary to retrieve the distribution of CO2 from its rovibrational transitions in the TIR. The instrument envisaged to test the new strategy is a Fourier transform spectrometer with two output ports hosting a FIR detector devoted to measuring the O2 transitions and a TIR detector devoted to measure the CO2 transitions. Instrumental and observational parameters of the proposed experiment have been defined by exploiting the heritage of both previous studies and operational limb sounders. The performance of the experiment has been assessed with two-dimensional (2-D) retrievals on simulated observations along a full orbit. For this purpose, optimal spectral intervals have been defined using a validated selection algorithm. Both precision and spatial resolution of the obtained CO2 distributions have been taken into account in the results–evaluation process. We show that the O2 spectral features significantly contribute to the performance of CO2 retrievals and that the proposed experiment can determine 2-D distributions of the CO2 volume mixing ratio with precisions of the order of 1 ppmv in the 10–50 km altitude range. The error budget, estimated for the test case of an ideal instrument and neglecting the spectroscopic errors, indicates that, in the 10–50 km altitude range, the total error of the CO2 fields is set by the random component. This is also the case at higher altitudes, provided the retrieval system is able to model the non-local thermal equilibrium conditions of the atmosphere. The best performance is obtained at altitudes between 20 and 50 km, where the vertical resolution ranges from 3 to 5 km, and the horizontal resolution is of the order of 300–350 km depending on latitude

Understanding the oxidative dehydrogenation of ethyl lactate to ethyl pyruvate over vanadia/titania

We studied the vapour-phase oxidative dehydrogenation (ODH) of ethyl lactate with air to give ethyl pyruvate over V2O5/TiO2 catalysts in a fixed-bed reactor. The nature of the vanadia species is changed by varying the vanadium surface density, and the corresponding structure of the VOx species was determined by XRD, UV-vis spectroscopy, XPS and H2-TPR. Monomeric and isolated vanadia species dominate at lower vanadium surface densities. As the surface density increases, two-dimensional polyvanadates and bulk-like vanadia crystallites become predominant. The activity per vanadium decreases with increasing vanadium surface density, indicating that the monomeric VOx species is better for pyruvate production and that the V–O–Ti bonds play an important role in the ODH of ethyl lactate. This is also confirmed by the superior catalytic performance of V2O5/TiO2 compared to vanadium supported on MgO, Al2O3, ZrO2 and CeO2. In situ DRIFT spectroscopy coupled with mass analysis shows that the reaction can involve three possible adsorption modes of ethyl lactate on the V2O5/TiO2 surface. Under anaerobic conditions, 2-hydroxypropionate forms, giving ethyl acetate as the major product. Conversely, under aerobic conditions, oxygen that is chemisorbed on V2O5/TiO2 is active and easily replenished from the gas phase, converting the ethyl-propionate-2-oxide intermediate into ethyl pyruvate.WZ thanks the China Scholarship Council for a PhD fellowship. EVRF thanks Generalitat Valenciana (project PROMETEOII/2014/004) and Ministerio de Economía y Competitividad (Spain) for projects MAT2013-45008-P, MAT2016-81732-ERC and RYC-2012-11427. This work is part of the Sustainable Chemistry Research Priority Area of the UvA (http://suschem.uva.nl)

Una nuova strategia per la misurazione della distribuzione di CO2 in stratosfera

Nella regione del TIR, le transizioni spettrali vibro-rotazionali della CO2 sono sfruttate per ricavare la distribuzione di P e T negli esperimenti spaziali. Oltre all’importanza di questi due parametri, la loro conoscenza è necessaria per ricavare la distribuzione di qualsiasi molecola dalle sue transizioni spettrali. Per ricavare P e T si assume di conoscere il VMR della CO2. L’accuratezza con cui si ricava la distribuzione della CO2 insieme a quelle di P e T non è sufficiente. Inoltre, il VMR della CO2 aumenta nel corso degli anni. Per questo, in questa tesi si propone una nuova strategia per misurare la CO2 usando uno strumento satellitare a scansione del lembo. L’idea è quella di sfruttare le transizioni rotazionali pure dell’O2 nella regione del FIR per ricavare P e T. Poiché queste transizioni traggono origine da un momento di dipolo magnetico la loro forza di riga è molto bassa. Tuttavia, grazie alla grande abbondanza dell’O2 in atmosfera e alla lunghezza dei cammini ottici, queste transizioni sono tra le più intense nello spettro atmosferico del FIR. Il satellite considerato è posto su un’orbita quasi polare e lo strumento osserva l’emissione del lembo atmosferico in direzione opposta a quella di volo. Lo strumento ipotizzato è uno spettrometro a trasformata di Fourier con due porte di output ospitanti un detector per la regione del FIR e uno per quella del TIR. La risoluzione spettrale è di 0.004 cm-1. Mentre il NESR è di 5 nW. Il campionamento geometrico verticale dell’atmosfera è di 3 Km mentre quello orizzontale è di circa 100 Km. Usando la teoria dell’optimal estimation sono stati selezionati due set di intervalli spettrali da analizzare, uno per la regione del FIR e l’altro per la regione del TIR. Con queste ipotesi sono stati effettuati test di retrieval su osservati simulati per valutare le performance del sistema ipotizzato. Si è dimostrato che le transizioni della CO2 nella regione del TIR non sono sufficienti per ricavare P e T insieme al proprio VMR con precisione soddisfacente e che l’uso dell’informazione derivante dal FIR fa aumentare la qualità del retrieval. Le performance dell’esperimento permettono di ricavare il VMR della CO2 con una precisione di circa 1 ppm tra 10 Km e 60 Km con una risoluzione verticale di 3 Km e una orizzontale di circa 2.5° di latitudine. Si è quindi dimostrato la validità della strategia proposta in questo studio

Waste management in Forlì-Cesena province: Life Cycle Assessment (LCA) of Forlì incinerator

This work assesses the environmental impact of a municipal solid waste incinerator with energy recovery situated in Forlì-Cesena province (Emilia-Romagna region, Italy). The methodology used is Life Cycle Assessment (LCA). This plant, opened in 2008, is able to submit 120000 t/year of waste. It uses dry flue gas abatement equipment, composed of a couple of fabric filters and lime and activated carbon spraying. It also includes a cogeneration plant, i.e. it simultaneously generates heat and power by a heat engine. As the plant tries to produce as few residues as possible, and it recovers a significant amount of energy, it already applies the best technologies available in waste treatment. This is why this study focuses mainly on the fate of the solid residues produced during incineration

Waste management in Forl\uec-Cesena province: Life Cycle Assessment (LCA) of Forl\uec incinerator

This work assesses the environmental impact of a municipal solid waste incinerator with energy recovery situated in Forl\uec-Cesena province (Emilia-Romagna region, Italy). The methodology used is Life Cycle Assessment (LCA). This plant, opened in 2008, is able to submit 120000 t/year of waste. It uses dry flue gas abatement equipment, composed of a couple of fabric filters and lime and activated carbon spraying. It also includes a cogeneration plant, i.e. it simultaneously generates heat and power by a heat engine. As the plant tries to produce as few residues as possible, and it recovers a significant amount of energy, it already applies the best technologies available in waste treatment. This is why this study focuses mainly on the fate of the solid residues produced during incineration

Pore Blocking by Phenolates as Deactivation Path during the Cracking of 4-Propylphenol over ZSM-5

Cracking of propyl side chains from 4-propylphenol, a model compound for lignin monomers, is studied for a commercial ZSM-5 zeolite catalyst. The decline of 4-propylphenol conversion with time on stream can be delayed by co-feeding water. FTIR spectroscopy shows the formation of chemisorbed phenolates during reactions and significant amounts of phenolics are detected by GC-MS of the extract from the spent catalysts. Thus, chemisorbed phenolates are identified as the main reason for deactivation in the absence of water. Regardless of the amount of co-fed water, substituted monoaromatics and polyaromatic species are formed. Comprehensive characterization of the spent catalysts including Raman and solid-state 27Al NMR spectroscopy, and thermogravimetric analysis points to a combination of deactivation processes. First, phenolates bind to Lewis acid sites within the zeolite framework and hinder diffusion unless they are hydrolyzed by water. In addition, light olefins created during the cracking process react to form a polyaromatic coke that deactivates the catalyst more permanently

Increase of ceria redox ability by lanthanum addition on Ni based catalysts for hydrogen production

The effects of lanthanum addition in Ni/CeO2 catalysts were investigated. The influence of synthetic procedures, namely, impregnation or coprecipitation of lanthanum and cerium oxide, were evaluated. Materials were analyzed by BET, AAS, DRIFT-MS, TPR, OSC, XRD, and SEM-EDX. Samples were tested in ethanol steam reforming (ESR). Both lanthanum-promoted samples exhibited a higher stability in time than nonpromoted catalyst. Nonetheless, catalytic behavior is strongly affected by the preparation method. TPR, OSC, and XRD analyses showed that the coprecipitation method allowed the best interaction between ceria and lanthana, leading to an increased redox ability and best catalytic performances as a result. A catalyst with a support prepared via the coprecipitation method showed ethanol conversion of 90% and hydrogen selectivity higher than 70% even after 60 h of reaction

Formation of carbon-induced nitrogen-centered radicals on titanium dioxide under illumination

Titanium dioxide is the most studied photocatalytic material and has been reported to be active for a wide range of reactions including oxidation of hydrocarbons and reduction of nitrogen. However, the molecular-scale interactions between the titania photocatalyst and dinitrogen are still debated, particularly in the presence of hydrocarbons. Here, we used several spectroscopic and computational techniques to identify interactions between nitrogen, methanol, and titania under illumination. Electron paramagnetic resonance spectroscopy (EPR) allowed us to observe the formation of carbon radicals upon exposure to ultraviolet radiation. These carbon radicals are observed to transform into diazo- and nitrogen-centered radicals (e.g., CHxN2* and CHxNHy*) during photocatalysis in nitrogen. In situ infrared (IR) spectroscopy under the same conditions revealed C-N stretching on titania. Furthermore, density functional theory (DFT) calculations reveal that nitrogen adsorption and the thermodynamic barrier to photocatalytic nitrogen fixation are significantly more favorable in the presence of methanol or surface carbon. These results provide compelling evidence that carbon radicals formed from the oxidation of hydrocarbons interact with dinitrogen, and suggest that the role of carbon-based ``hole scavengers\u27\u27 and the inertness of nitrogen atmospheres should be reevaluated in the field of photocatalysis

Highly Selective Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by Mesoporous Vanadia 12Titania

The direct oxidative dehydrogenation of lactates with molecular oxygen is a \u201cgreener\u201d alternative for producing pyruvates. Here we report a one-pot synthesis of mesoporous vanadia 12titania (VTN), acting as highly efficient and recyclable catalysts for the conversion of ethyl lactate to ethyl pyruvate. These VTN materials feature high surface areas, large pore volumes, and high densities of isolated vanadium species, which can expose the active sites and facilitate the mass transport. In comparison to homogeneous vanadium complexes and VOx/TiO2 prepared by impregnation, the meso-VTN catalysts showed superior activity, selectivity, and stability in the aerobic oxidation of ethyl lactate to ethyl pyruvate. We also studied the effect of various vanadium precursors, which revealed that the vanadium-induced phase transition of meso-VTN from anatase to rutile depends strongly on the vanadium precursor. NH4VO3 was found to be the optimal vanadium precursor, forming more monomeric vanadium species. V4+ as the major valence state was incorporated into the lattice of the NH4VO3-derived VTN material, yielding more V4+ 12O 12Ti bonds in the anatase-dominant structure. In situ DRIFT spectroscopy and density functional theory calculations show that V4+ 12O 12Ti bonds are responsible for the dissociation of ethyl lactate over VTN catalysts and for further activation of the deprotonation of \u3b2-hydrogen. Molecular oxygen can replenish the surface oxygen to regenerate the V4+ 12O 12Ti bonds