Aimaro Sanna

Renewable Chemical Commodity Feedstocks from Integrated Catalytic Processing of Pyrolysis Oils

A Little Help from Hydrogen Biomass may one day displace petroleum as the chemical industrys primary feedstock. Currently, though, the primary hurdle for incorporating plant-derived material into existing process feeds is the high proportion of oxygen in its molecular frameworks. Rapid heating of the biomass followed by high-temperature treatment with zeolite catalysts can yield tractable quantities of useful commodity compounds such as ethylene and benzene, but much of the carbon is wasted in the process—diverted either toward gaseous CO and CO2, or solid coke. Vispute et al. (p. 1222) show that an intermediate step, in which hydrogen is catalytically incorporated into the heated material prior to zeolite treatment, can substantially raise the yield of useful products by reducing susceptibility to coking. The addition of hydrogen helps boost the yield of useful commodity compounds from pyrolized biomass. Fast pyrolysis of lignocellulosic biomass produces a renewable liquid fuel called pyrolysis oil that is the cheapest liquid fuel produced from biomass today. Here we show that pyrolysis oils can be converted into industrial commodity chemical feedstocks using an integrated catalytic approach that combines hydroprocessing with zeolite catalysis. The hydroprocessing increases the intrinsic hydrogen content of the pyrolysis oil, producing polyols and alcohols. The zeolite catalyst then converts these hydrogenated products into light olefins and aromatic hydrocarbons in a yield as much as three times higher than that produced with the pure pyrolysis oil. The yield of aromatic hydrocarbons and light olefins from the biomass conversion over zeolite is proportional to the intrinsic amount of hydrogen added to the biomass feedstock during hydroprocessing. The total product yield can be adjusted depending on market values of the chemical feedstocks and the relative prices of the hydrogen and biomass.

Post-processing pathways in carbon capture and storage by mineral carbonation (CCSM) towards the introduction of carbon neutral materials

Carbon dioxide capture and storage by mineral carbonation (CCSM) is a technology that can potentially sequester billions of tonnes of carbon dioxide (CO2) per year. Despite this large potential, the costs of CCSM are currently too high for a large deployment of the technology and new systems are being investigated to attempt to overcome these limitations. To improve this situation, the successful development of post-processing routes creating marketable carbon neutral products could help the deployment of mineral carbonation. This work investigates the current market for CCSM products and the role they can play in decreasing the overall cost of CCSM technology. The current global market for the raw commodities, primarily cement additives, fillers and iron ore feedstock which could be produced by rock and/or industrial waste/by-product mineralisation, is about 27.5 Gt and can be easily flooded assuming 10% of the global CO2 emissions sequestered by CCSM. The CCSM technology chosen will play a very important role in the products created, available post-processing routes and accessible markets if the resultant materials are of high purity. Low-value applications such as fill for land reclamation may represent the only viable opportunity at the current state of the technology, bearing in mind that these materials are competing with low-cost materials (i.e. crushed rock) and that the size distribution of the carbonated materials may need significant alteration to make them potentially useful. However, there is a lack of information available on the quality of the CCSM products towards access to high-value markets such as micro-silica and PCC. In summary, CCSM post-processing might be viable only in niche high-value markets, while low-value applications such as land/mine reclamation are potentially more feasible and could be able to absorb Gts of CCSM products.

Bio-oil and bio-char from low temperature pyrolysis of spent grains using activated alumina.

The pyrolysis of wheat and barley spent grains resulting from bio-ethanol and beer production respectively was investigated at temperatures between 460 and 540 °C using an activated alumina bed. The results showed that the bio-oil yield and quality depend principally on the applied temperature where pyrolysis at 460 °C leaves a bio-oil with lower nitrogen content in comparison with the original spent grains and low oxygen content. The viscosity profile of the spent grains indicated that activated alumina could promote liquefaction and prevent charring of the structure between 400 and 460 °C. The biochar contains about 10-12% of original carbon and 13-20% of starting nitrogen resulting very attractive as a soil amendment and for carbon sequestration. Overall, value can be added to the spent grains opening a new market in bio-fuel production without the needs of external energy. The bio-oil from spent grains could meet about 9% of the renewable obligation in the UK.

Nannochloropsis algae pyrolysis with ceria-based catalysts for production of high-quality bio-oils.

Pyrolysis of Nannochloropsis was carried out in a fixed-bed reactor with newly prepared ceria based catalysts. The effects of pyrolysis parameters such as temperature and catalysts on product yields were investigated. The amount of bio-char, bio-oil and gas products, as well as the compositions of the resulting bio-oils was determined. The results showed that both temperature and catalyst had significant effects on conversion of Nannochloropsis into solid, liquid and gas products. The highest bio-oil yield (23.28 wt%) and deoxygenation effect was obtained in the presence of Ni-Ce/Al2O3 as catalyst at 500°C. Ni-Ce/Al2O3 was able to retain 59% of the alga starting energy in the bio-oil, compared to only 41% in absence of catalyst. Lower content of acids and oxygen in the bio-oil, higher aliphatics (62%), combined with HHV show promise for production of high-quality bio-oil from Nannochloropsis via Ni-Ce/Al2O3 catalytic pyrolysis.

Bio-oil deoxygenation by catalytic pyrolysis: new catalysts for the conversion of biomass into densified and deoxygenated bio-oil.

This work proposes an innovative catalytic pyrolysis process that converts bio-refinery residues, such as spent grains, into intermediate bio-oil with improved properties compared to traditional bio-oils, which allows the use of existing crude-oil refinery settings for bio-oil upgrading into fuels. The integration of bio-oil into a crude-oil refinery would decrease the economic disadvantage of biomass compared to fossil fuels. The catalytic pyrolysis was able to produce bio-oil with a lower O and N content and high levels of aliphatics and H by using activated serpentine and olivine at 430-460 °C. The activated materials seem to be beneficial to the bio-oil energy content by increasing it from less than 20 MJ kg(-1) in the original biomass to 26 MJ kg(-1). Approximately 70-74 % of the starting energy remains in the bio-oil using activated olivine (ACOL) and activated serpentine (ACSE) at 430 °C, whereas only 52 % is retained using alumina (ALU) at the same temperature. There was a strong reduction of the O content in the bio-oils, and the deoxygenation power decreased in the following order: ACOL>ACSE>ALU. In particular, ACOL at 430-460 °C was able to reduce the O content of the bio-oil by 40 %. The oxygenated bio-oil macromolecules interact in the catalysts active sites with the naturally present metallic species and undergo decarboxylation with the formation of C(5)-C(6) O-depleted species.

Ceria promoted deoxygenation and denitrogenation of Thalassiosira weissflogii and its model compounds by catalytic in-situ pyrolysis.

Pyrolysis of microcrystalline cellulose, egg white powder, palm-jojoba oils mixtures Thalassiosira weissflogii model compounds was performed with CeO2 at 500°C, to evaluate its catalytic upgrading mechanism. Light organics, aromatics and aliphatics were originated from carbohydrates, proteins and lipids, respectively. Dehydration and decarboxylation were the main reactions involved in the algae and model compounds deoxygenation, while nitrogen was removed as NH3 and HCN. CeO2 increased decarbonylation reactions compared to in absence of catalyst, with production of ketones. The results showed that the catalysts had a significant effect on the pyrolysis products composition of T. weissflogii. CeO2, NiCeAl2O3 and MgCe/Al2O3 catalysts increased the aliphatics and decreased the oxygen content in bio-oils to 6-7 wt% of the algae starting O2 content. Ceria catalysts were also able to consistently reduce the N-content in the bio-oil to 20-38% of that in the parent material, with NiCe/Al2O3 being the most effective.

Glycerol Production and Transformation: A Critical Review with Particular Emphasis on Glycerol Reforming Reaction for Producing Hydrogen in Conventional and Membrane Reactors

Glycerol represents an emerging renewable bio-derived feedstock, which could be used as a source for producing hydrogen through steam reforming reaction. In this review, the state-of-the-art about glycerol production processes is reviewed, with particular focus on glycerol reforming reactions and on the main catalysts under development. Furthermore, the use of membrane catalytic reactors instead of conventional reactors for steam reforming is discussed. Finally, the review describes the utilization of the Pd-based membrane reactor technology, pointing out the ability of these alternative fuel processors to simultaneously extract high purity hydrogen and enhance the whole performances of the reaction system in terms of glycerol conversion and hydrogen yield.

Micro-Silica for High-End Application from Carbon Capture and Storage by Mineralisation

Waste silica remaining after the Carbon Capture and Storage by Mineral carbonation (CCSM) could represent a potential pozzolan material for partial replacement in concrete. The objective of this work was the production and testing of cement gel cubes with the residual-silica by-product obtained from the accelerated carbonation of Mg-silicate rocks. The silica produced was characterised in terms of its chemical composition, morphology and LOI. Also, the silica was used as an additive to the cement (CEM I class) in order to assess the effect on (28 days) compressive strength in comparison with a cement control specimen. The influence of different cement replacement percentages (5% and 10wt.% silica) were determined by measuring initial setting times and compressive strength. The compressive strength of the cement specimens with 5 and 10wt.% silica as pozzolan replacement of Portland cement were 3% and 8% higher than the control cubes indicating that the residual silica powder may have pozzolanic properties. However, high LOI and magnesium content might represent a limit in high-end applications and further work is required to identify optimised CCSM conditions able to reduce the impurities in the silica by-product and to establish their potential as a pozzolan.

Upgrading bio-oils obtained from bio-ethanol and bio-diesel production residues into bio-crudes using vis-breaking

Upgrading of bio-oils obtained from rape seed meal and wheat spent grains was carried out by a Thermo-t process similar to vis-breaking at 350, 400 and 410 °C at pressure ranging from 10 to 40 bars of nitrogen. About 35–40% of the energy contained in the virgin biomasses was converted into bio-crudes with 3–7 wt% oxygen. The effect of temperature on yield and quality of the bio-crudes from the Thermo-t process was studied. Overall, the process generates two different upgraded products, a liquid called bio-crude and a solid namely bio-coke. The experimental data show an effective upgrading of pyrolytic oils leading to the formation of 10–20 wt% of bio-crude with oxygen contents below 10 wt% and volatiles distribution close to conventional crude oil. The energy needed by the overall processes is estimated to be about 17% of the feedstock energy content and this value is comparable to a crude oil refinery where the energy need is about 15%. An important chemical transformation of bio-crude functionality from mostly aromatic pyrolytic bio-oil to a mainly aliphatic bio-crude has been assessed, representing a low cost solution for the high oxygen content of bio-oils. Furthermore, the addition of water was evaluated in order to enhance the deoxygenation of pyrolytic bio-oil in comparison to work done on upgrading crude-oil heavy vacuum residues.

A novel Ru–polyethersulfone (PES) catalytic membrane for highly efficient and selective hydrogenation of furfural to furfuryl alcohol

A novel catalytic membrane has been synthesised, characterised and evaluated for the selective hydrogenation of furfural to furfuryl alcohol. Unlike conventional methods, involving high pressure and high H2 : feed ratios, this work proposes an innovative ruthenium based Catalytic Membrane Reactor (CMR) to overcome mass transfer limitations, resulting in low H2 requirements, high catalytic activity and high selectivity towards furfuryl alcohol. A UV-curable hydrophilic anionic monomer acrylic acid was used as a coating material on a commercial PES membrane and subsequently Ru nanoparticles were added. The hydrogenation of furfural was carried out in a customised catalytic membrane reactor under mild conditions: 70 °C and 7 bar, exhibiting high catalytic activity towards furfuryl alcohol (selectivity >99%) with turnover frequency (TOF) as high as 48 000 h−1, 2 orders of magnitude higher than those obtained so far.