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ZnO supported on zirconia (ZnO/ZrO2) catalyses methanol synthesis with high selectivity and stability at temperatures >300 °C, where methanol dehydration to hydrocarbons can also occur. When combined with ZSM-5 a CO2 conversion of 14-15 % with an aromatics selectivity of 73-76 % within the hydrocarbons has been reported for a direct syngas to aromatics process [1,2]. The aromatization on Brønsted acid sites within the zeolite pores involves cyclization and hydrogen transfer reactions. The broadly accepted hydrocarbon dual cycle mechanism states that olefins act as hydrogen acceptors in bimolecular hydrogen transfer reactions that produce alkanes and aromatics. This co-production of alkanes limits the selectivity to aromatics. Promoting the zeolite with transition metals can favour the aromatization reaction via an additional dehydrogenation functionality [3]. However, the methanol synthesis over ZnO/ZrO2 is favoured at high pressure and high hydrogen concentration; by contrast the methanol- to-aromatics (MTA) process, occurs with no hydrogen in the feed to promote the hydrogen transfer reactions. This work investigates the combination of ZnO/ZrO2 with ZSM-5 of various acid site densities, for direct conversion of syngas to aromatics. The mixing ratio and operating conditions were optimized to increase the COx conversion and aromatics selectivity.

Direct conversion of synthesis gas to olefins (STO) is an attractive way of producing large volume base chemicals currently almost exclusively obtained from crude oil. It is a simplification of a two-step process of methanol synthesis followed by methanol to olefins (MTO), avoiding methanol condensation and purification and having fewer recycle streams. Recent literature reports that a combination of different mixed metal oxides or supported metal oxides, such as ZnAl2O4, ZnGa2O4, ZnCr2O4, ZnO/ZrO2 or In2O3/ZrO2, can catalyze methanol synthesis at temperatures >380 °C where methanol dehydration to olefins can occur over narrow pore zeolites SSZ-13 or SAPO-34 [1-3]. However, literature is typically focusing on one type of each component. Here we report a comprehensive comparison between ZnAl2O4, ZnGa2O4 and ZnO-ZrO2 catalysts for methanol synthesis and for syngas to olefines when combined with SAPO-34. This includes fundamental characterization using BET, ICP and XRD and in-depth characterization using operando XAS and DRIFTS.

It has been estimated that 302 million tons of plastic waste were generated worldwide in 2015 [1]. Unfortunately, there is still a need for burning plastic waste to avoid it being disposed on landfills where no value of the products is regained. When incinerating a plastic product, the fraction of the energy that went into producing the plastic can be recovered as electricity and heat. Closing the carbon loop from plastic incineration by capturing and recycling CO2 to produce new plastic will minimize the climate impact of the current emissions and reduce the need for fossil resources in plastic production. Promoted Fisher-Tropsch catalysts can convert CO2 and H2 into ethylene and propylene with yields up to 60% [2]. This yield is close to the theoretical limit by the Anderson-Schulz-Flory distribution, which is still considered to be a limitation for the Fisher-Tropsch process. An alternative route for converting CO2 into hydrocarbon products is the combination of methanol synthesis and the methanol to hydrocarbon reaction. The methanol synthesis is equilibrium limited and a strategy to overcome this is to combine a methanol synthesis catalyst with a zeolite catalyst within one reactor [3,4]. In the temperature range of 300 to 420 °C, necessary for the zeolite to be active, the traditional Cu/ZnO/Al2O3 methanol synthesis catalyst cannot be used. At these temperatures, severe sintering of the metallic copper deactivates the catalyst. Furthermore, the hydrogen spill-over effect for the metallic copper results in the hydrogenation of the olefins formed in the zeolite [5]. To overcome these limitations, metal oxides capable of converting CO2 and H2 to methanol at relatively high temperatures have been synthesized and tested.

Molybdenum oxide (5 to 20 wt.%) supported on calcium or strontium hydroxyapatite were investigated as catalysts for selective oxidation of methanol to formaldehyde. These catalysts were both active and selective, with a maximum yield achieved at 95% conversion and 96% selectivity. The main byproducts were CO (3.2%) and dimethyl ether (DME, 0.7%). The catalytic performance of the catalysts was measured for up to 600 h at 350°C. Compared to an industrial iron molybdate catalyst, the hydroxyapatite based catalysts deactivated slower. The active species were found to be a surface layer of MoOx on the hydroxyapatite support, while excess molybdenum formed crystalline (Ca/Sr)MoO4, acting as a reservoir replenishing surface MoOx lost by volatilization with methanol. The excess molybdenum in the form of (Ca/Sr)Mo4 was found to volatilize significantly slower than the excess MoO3 in iron molybdate catalysts. The combination of high activity and selectivity with low rate of Mo volatilization makes this class of catalysts interesting for industrial production of formaldehyde.

In this study, 10 wt% MoO3 supported on hydroxyapatite (HAP, Ca5(OH)(PO4)3) pellets were investigated as catalysts for the selective oxidation of methanol to formaldehyde. HAP was synthesized by co-precipitation and pressed into industrial sized pellets with different densities (1.18–1.76 g cm−3) to investigate the influence of pellet density and porosity on the catalytic performance. The pellets were wet impregnated to obtain 10 wt% MoO3. The catalysts were characterized by X-ray diffraction (XRD), N2 physisorption, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES) and Hg-porosimetry. The catalytic performance was evaluated at 250–400 °C for up to 100 h continuous operation in a single pellet reactor with 300 NmL min−1, 5 vol% MeOH, and 10 vol% O2 in N2. The MoO3/HAP pellets lost between 10% and 23% of their initial activity while an industrial MoO3/Fe2(MoO4)3 reference catalyst lost ∼11% within 100 h on stream at 350 °C. Despite the MoO3/HAP catalysts not outperforming the FeMo reference, it was still deemed of interest for further study and optimization as the difference was relatively small. Especially since the pellets weight loss due to Mo volatilization was >70% lower compared with the FeMo catalysts within a 118.5 h test. A random pore model, together with overall effectiveness factor calculations for both powder and pellets, was used to calculate the pellet activity from measured powder activity, providing reasonable agreement between the calculated and the observed rate constants for the pellets. An increase in both activity and selectivity to formaldehyde was obtained with decreasing pellet density, due to decreasing pore diffusion limitations of both methanol into and forma

The treatment of biomass-derived fast pyrolysis vapors with solid acid catalysts (in particular HZSM-5 zeolite) improves the quality of liquid bio-oils. However, due to the highly reactive nature of the oxygenates, the catalysts deactivate rapidly due to coking. Within this study, the deactivation and product yields using steam-treated phosphorus-modified HZSM-5/γ-Al2O3 and bare γ-Al2O3 was studied with analytical Py-GC. While at a fixed catalyst temperature of 450 °C, a rapid breakthrough of oxygenates was observed with increased biomass feeding, this breakthrough was delayed and slower at higher catalyst temperatures (600 °C). Nevertheless, at all (constant) temperatures, there was a continuous decrease in the yield of oxygen-free hydrocarbons with increased biomass feeding. Raising the reaction temperature during the vapor treatment could successfully compensate for the loss in activity and allowed a more stable production of oxygen-free hydrocarbons. Since more biomass could be fed over the same amount of catalyst while maintaining good deoxygenation performance, this strategy reduces the frequency of regeneration in parallel fixed bed applications and provides a more stable product yield. The approach appears particularly interesting for catalysts that are robust under hydrothermal conditions and warrants further investigations at larger scales for the collection and analysis of liquid bio-oil.

Kort katalysatorlevetid, stort produktionsvolumen og det evige behov for procesforbedringer har øget behovet for at forstå deaktiveringen af den industrielle jernmolybdat-katalysator samt udvikling af nye, mere stabile katalysatorer til selektiv oxidation af metanol til formaldehyd.

Atmospheric hydrodeoxygenation (HDO) of wheat straw fast pyrolysis vapors was studied as a promising route for the production of renewable liquid transportation fuels. The performance of TiO2-supported Pt (0.5 wt%) and MoO3 (10 wt%) catalysts was compared to an industrial Mo-based catalyst using a bench scale reactor operated at atmospheric pressure and up to high biomass-to-catalyst ratios (B:C). Mass and energy balances were complemented by detailed bio-oil characterization including advanced methods such as GC×GC-ToF/MS or -FID and 13C NMR. At 50 vol% H2, all three HDO catalysts effectively reduced the oxygen content of the bio-oils to ∼7–12 wt% (dry basis) compared to a non-catalytic reference (23 wt% O). MoO3/TiO2 was least efficient in conversion of acids (TAN = 28 mg per KOH), while Pt/TiO2 and MoO3/Al2O3 obtained oils with TAN ∼ 13 mg KOH/g (non-catalytic = 66 mg KOH/g). Compared to the TiO2-supported catalysts, the industrial Mo/Al2O3 catalyst produced higher yields of coke at the expense of condensed bio-oil. MoO3/TiO2 performed similar to Pt/TiO2 in terms of deoxygenation and energy recovery of condensed bio-oil, and by increasing the H2 concentration to 90 vol% the energy recovery of bio-oil increased to 39 and 42% at 8 and 10 wt% O (d.b.), respectively. Pt/TiO2 showed the highest selectivity to aliphatics and the lowest coke yields, e.g. the coke yield at B:C ∼ 8 was only 0.6 wt% of fed biomass. This study demonstrates that by using low-pressures of hydrogen and appropriate HDO catalysts, the quality of bio-oil can be improved without severely compromising its quantity (carbon yield) as observed under catalytic fast pyrolysis conditions.

Alkali earth metal molybdates (MMoO4, M = Mg, Ca, Sr, and Ba) were investigated as catalysts for the selective oxidation of methanol to formaldehyde in the search for more stable alternatives to the current industrial iron molybdate catalyst. The catalysts were prepared by either sol-gel synthesis or co-precipitation with both stoichiometric ratio (Mo:M = 1.0) and 10 mol% to 20 mol% excess Mo (Mo:M = 1.1 to 1.2). The catalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption, Raman spectroscopy, temperature programmed desorption of CO2 (CO2-TPD), and inductively coupled plasma (ICP). The catalytic performance of the catalysts was measured in a lab-scale, packed bed reactor setup by continuous operation for up to 100 h on stream at 400 °C. Initial selectivities towards formaldehyde of above 97% were achieved for all samples with excess molybdenum oxide at MeOH conversions between 5% and 75%. Dimethyl ether (DME) and dimethoxymethane (DMM) were the main byproducts, but CO (0.1%–2.1%) and CO2 (0.1%–0.4%) were also detected. It was found that excess molybdenum oxide evaporated from all the catalysts under operating conditions within 10 to 100 h on stream. No molybdenum evaporation past the point of stoichiometry was detected.

Steam treated HZSM-5 with different Si/Al ratios were tested as catalysts for the upgrading of wheat straw pyrolysis vapors and their performance was compared to hierarchical counterparts, which were prepared by desilication followed by acid washing. Pyrolysis vapors were generated in an ablative system, hot gas filtered, and upgraded in an ex-situ catalyst bed to remove oxygen functionalities and reduce the oils' total acid number (TAN). Besides elemental analysis and TAN, the collected liquids were analyzed for water, chemical composition by gas chromatography mass spectrometry with flame ionization detection (GC–MS/FID), size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and selectively by 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear single-quantum correlation (2D HSQC) NMR. Hierarchical and conventional catalysts were analyzed with X-ray fluorescence (XRF), ammonia temperature-programmed desorption (NH3-TPD) and ethylamine TPD, N2 and Ar-physisorption, transmission electron microscopy (TEM) and X-ray diffraction (XRD) to investigate changes induced by the desilication process. In addition, samples were analyzed after several reaction and regeneration cycles to investigate catalyst stability. The hierarchical samples showed an increased coking propensity compared to their parent version. The introduction of mesopores after desilication of HZSM-5 with molar Si/Al ratios of 29 and 39 lead to prolonged activity in deoxygenation and improved carbon recovery in the collected oil fractions compared to the parent counterparts. The results indicate that mild deoxygenation may be a viable way of pretreating pyrolysis oil before co-processing with fossil oil in refineries.

Formaldehyde is the most important aldehyde commercially available as it is an irreplaceable C1 building block for higher-valued products [1]. The annual global production of formaldehyde is expected to increase with 4.8-5.8% per year and reach 36.6 million tons by 2026 [2, 3]. Formaldehyde is mainly produced through either the silver process or the Formox process [1]. In the Formox process, methanol is selectively oxidized over an iron molybdate catalyst (MoO3/Fe2(MoO4)3), which achieve high selectivities (92-95%) at high conversions (>99%) [1]. The catalyst is however not stable under the reaction conditions due to formation of volatile molybdenum compounds [4]. The alkali earth metal molybdates have been reported to have high thermal stability [5], with expected lower volatility of Mo in MeOH atmosphere, and their properties as catalysts for selective oxidation of methanol are scarcely investigated in the literature.

HZSM-5 extrudates, its two constituents (HZSM-5 zeolite and alumina binder), and SiC for reference were tested after steam treatment for the upgrading of wheat straw fast pyrolysis (FP) vapors from an ablative bench scale system. In addition, mesoporosity was added to the HZSM-5 crystals of the zeolite/Al2O3 extrudates by desilication, which decreased the microporous volume and led to enhanced weak acidity and less strong acidity compared to the parent extrudates. For increasing biomass-to-catalyst ratios (w/w, B:C), oils were collected and analyzed for elemental composition, total acid number (TAN), moisture, molecular weight, evaporation characteristics, and chemical composition by gas chromatography mass spectrometry with flame ionization detection (GC-MS/FID), 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear single-quantum correlation (2D HSQC) NMR. Compared to Al2O3, catalysts containing HZSM-5 promoted aromatization and limited the coke formation due to its shape selective micropores. Nevertheless, Al2O3 was effective in deoxygenation. At B:C ~7, 23 wt-% carbon/25 % energy recovery in the oil fraction was obtained while reducing the oxygen content by 45 % relative to a thermal reference oil fraction obtained over a SiC bed. As such, Al2O3 offers certain benefits compared to HZSM-5 based catalysts due to its lower cost and better hydrothermal stability with respect to acidity. At a catalyst temperature of 500 °C, the introduction of mesopores to HZSM-5 extrudates led to higher energy recovery as oil compared to the parent HZSM-5 extrudates. At B:C = 6.3, 23 wt-% carbon/26% energy recovery in the oil phase was achieved while removing 45% of the oxygen functionalities relative to the thermal reference bio-oil. Compared to deep deoxygenation for direct hydrocarbon production, mild deoxygenation improved the energy recoveries of the oil fractions a

In this work alkali earth metal molybdate catalysts with Mo:M = 1.0 and 1.1 stoichi-ometry have been synthesized and tested for the selective oxidation of methanol to formaldehyde in a lab scale fixed bed reactor setup. Excess Mo gave better initial activity and selectivity but a higher rate of deactivation during 100 h on stream.

In this work, we provide detailed information on the change in product distribution and bio-oil quality during extended feeding of biomass derived fast pyrolysis vapors over ZSM-5. The effect of catalyst deactivation by coking on the resulting oil product characteristics was clarified in order to determine when the vapor upgrading should be stopped and the regeneration initiated. Obtaining a stable catalyticfast pyrolysis (CFP) oil while maintaining good energy recovery is important within the context of potential coprocessing of these oils with petroleum feedstocks via fluid catalytic cracking (FCC) or hydrotreatmentof the whole CFP oil. Wheat straw derived fast pyrolysis vapors were upgraded in an ex-situ fixed bed reactor containing a steamed ZSM-5 catalyst at 500 °C. Oils were collected bothfor runs starting the upgrading over a fresh (or regenerated) catalyst and for runs which were continued over an increasingly coked zeolite. The oils were characterized for water content, elemental analysis, total acid number (TAN), chemical composition by gas chromatography mass spectrometry with flame ionization detection (GC-MS/FID), size exclusion chromatography (SEC), evaporation characteristics by thermogravimetric analysis (TGA), 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear single-quantum correlation (2D HSQC) NMR. With increasing biomass-to-catalyst mass ratio (B:C), the yield of deoxygenated hydrocarbons decreased, accompanied by a breakthrough of primary pyrolysis vapors leading to an increasing organic liquid yield. The oxygen content of the condensed, phase separated oil fraction increased and the molar O/C ratio of 0.05 and TAN of6 mg KOH/g for oil collected during B:C = 0–1.1 increased to O/C = 0.18 and TAN = 14 mg KOH/g for oil collected during B:C = 3.6–6.2. Oil produced at 90% reduced catalyst amount and B:C = 0–6.5 and 0–12.9 increased the carbon recovery into the oil product to 23% and 27%, respective

Here, we report the synthesis and characterization of hierarchical zeolite materials with MEL, BEA and FAU structures. The synthesis is based on the carbon templating method with an in situ-generated carbon template. Through the decomposition of methane and deposition of coke over nickel nanoparticles supported on silica, a carbon–silica composite is obtained and exploited as a combined carbon template/silica source for the zeolite synthesis. The mesoporous zeolite materials were all prepared by hydrothermal crystallization in alkaline media followed by removal of the carbon template by combustion, which results in zeolite single crystals with intracrystalline pore volumes of up to 0.44 cm3 g−1. The prepared zeolite structures are characterized by XRD, SEM, TEM and N2 physisorption measurements.

The oxidative synthesis of acetonitrile from ethylamine was studied using a supported ruthenium catalyst. The reaction was conducted in both batch and flow processes and high conversions (over 85%) were achieved in both cases. Selectivity of both reactions was improved by optimisation of reaction conditions, achieving over 90% selectivity in the batch process and 80% selectivity in the continuous flow process. The use of a selective solid catalyst that utilises a feedstock that can be derived from biomass, dioxygen as the oxidant and water as the solvent represents a new, green route for the independent and efficient production of acetonitrile.

Synthesis of amides by aerobic oxidative coupling of alcohols or aldehydes with amines via intermediate formation of methyl esters is highly efficient and selective when using a catalytic system comprised of supported gold nanoparticles and added base in methanol.

Zeolite catalyzed deoxygenation of small oxygenates present in bio-oil or selected as model compounds was performed under Methanol-to-Hydrocarbons (MTH) like reaction conditions using H-ZSM-5 as the catalyst. Co-feeding of the oxygenates with methanol generally decreases catalyst lifetime due to coking and results in higher selectivity towards aromatics compared to conversion of pure methanol. The reaction pattern of the different oxygenates did not simply follow the effective H/C ratio of the additives since structural isomers with identical effective H/C ratios showed significant differences with respect to catalyst lifetime and product selectivity. A distinct positive effect on catalyst lifetime was observed for methanol dilution. Thus, the conversion capacity of the catalyst was up to 10 times higher when the reactant was diluted in methanol. We observe that in particular acid/ester functionalities favor oxygen removal through decarbonylation over dehydration which preserves hydrogen in the hydrocarbon product mixture. By employing 13C labeled substrates we confirmed the incorporation of carbon into the hydrocarbon products as well as a pronounced preference of the additive carbon towards incorporation into aromatic compounds.

Hovedemnet for denne afhandling er zeolit katalyseret konversion af oxygenater til kulbrintebaseret brændstof og kemikalier, og konversion af ethan til højere kulbrinter er også blevet undersøgt. Det første kapitel er en kort introduktion til konceptet ”the methanol economy”, som er et fremtidsscenarie, hvor methanol fungerer som energibærer og byggesten i den kemiske industri. Det andet kapitel er et litteraturstudium af Mobils ”methanol to hydrocarbons” proces. Her gives et overblik over processens historie, de anvendte katalysatorers egenskaber og reaktionsmekanismen. I det tredje kapitel beskrives en række forsøg omhandlende co-konversion af ethan og methanol over en kommerciel H-ZSM-5 zeolite imprægneret med gallium og/eller molybdan. Formålet var at undersøge, om tilstedeværelsen af methanol i fødestrømmen kunne forøge konversionen af ethan, men i alle tilfælde blev det modsatte observeret, idet tilstedeværelsen af methanol undertrykker konversionen af ethan. Dette skyldes højst sandsynligt simpel konkurrence om de aktive sites. Isotopmarkningsstudier udført med 13C market methanol og umarket ethan viste, at i de første minutter af reaktionen, bliver der inkorporeret store mængder carbon fra ethan i produkterne. Dette tilskrives en stokiometrisk reaktion mellem ethan og metaloxider pa katalysatoren, hvorved ethan oxideres til ethen, som uden videre bliver konverteret og inkorporeret i produkterne. Fjerde kapitel omhandler konversion af methanol, ethanol, 2-propanol og 1-butanol til carbonhydrider over forskellige zeolit katalysatorer. Når 2-propanol eller 1-butanol bliver konverteret over H-ZSM-5 er katalysatoren i stand til at konvertere mere end 25 gange så meget reaktant for deaktivering i forhold til konversion af methanol eller ethanol. Ydermere ændrer selektiviteten sig under forsøget, når C3+ alkoholer konverteres over H-ZSM-5, The main focus of this thesis is zeolite catalyzed conversion of oxygenates to hydrocarbon fuels and chemicals. Furthermore, conversion of ethane to higher hydrocarbons has also been studied. After a brief introduction to the concept of “the methanol economy” in the first chapter, the second chapter is a literature study of Mobil’s “methanol to hydrocarbons” (MTH) process, giving an overview of the history of the process, the nature of the employed catalysts, and the reaction mechanism. In the third chapter, a series of experiments concerning co conversion of ethane and methanol over a commercial H-ZSM-5 zeolite impregnated with gallium and/or molybdenum is described. The object was to investigate if the presence of methanol in the feed could enhance the conversion of ethane, but in all cases the opposite is observed; the presence of methanol actually suppresses the conversion of ethane. This suppression of ethane conversion is most likely due to simple composition for the active sites. Isotopic labeling studies performed with 13C labeled methanol and unlabeled ethane showed that in the very first minutes of the reaction, large amounts of carbon atoms from ethane are incorporated into the products. This observation is attributed to a stoichiometric reaction between ethane and the metal oxide species in the catalyst, leading to the oxidation of ethane to ethene, which is readily converted and incorporated into the products. Conversion of methanol, ethanol, 2-propanol, and 1 butanol to hydrocarbons over various zeolite catalysts is studied in Chapter 4. When 2-propanol or 1-butanol is converted over H-ZSM-5, the total conversion capacities of the catalyst are more than 25 times higher than for conversion of methanol and ethanol. Furthermore, for conversion of C3+ alcohols, the selectivity shifts during the experiment, and after around one third of the total run time, the product mixture consists almost exclusively of alkenes, which is in