Towards a Norwegian Spruce Bark Biorefinery

This project explores the development of a potential biorefinery based on Norwegian spruce bark using Soxhlet, microwave pyrolysis and subcritical water extraction processes in order to yield chemicals, materials and bioenergy. Spruce bark contains 18% ethanol extractives (Soxhlet extraction) including a significant amount of phenols and condensed tannins (39 mg GAE/g) commensurate with lignocellulosic matter. Component analysis of spruce bark revealed: cellulose (25%), hemicellulose (8%), lignin (25%), ethanol extractives (18%), ash (2%), moisture (9.2%), C (47.64%), H (5.91%), N (0.23%) and HHV (17.3 MJ/kg). Depending on the processing temperature, microwave pyrolysis of spruce bark yielded bio-oil (8%-14%) and bio-char (65%-75%) depending on pyrolysis temperature. The bio-oil mainly comprised phenolic compounds, such as: phenol, guaiacol, eugenol, and 2-methoxy-4-methylphenol, whilst the biochar gave a relatively high calorific value (26.6 MJ/kg at 240℃), compared with native spruce bark (22.4 MJ/kg), thus showing energy densification. Subcritical water extraction (SWE) yielded organic extractives (3%-8%), sugars (3%-6%) and residues (60%-70%). The organic extractive comprises phenols and furfurals, and a range of sugars, notably glucose and rhamnose, demonstrating the potential of SWE as a hydrolytic process for spruce bark. The sugars can be used for downstream fermentation processes, and the residues may be converted into nanocellulose or used as fuel (bioenergy). Thus, within the context of a potential biorefinery spruce bark affords high-value chemicals (phenols, tannins etc.), fermentable sugars, bio-char and cellulosic materials

Microwave-Assisted Defibrillation of Microalgae

The first production of defibrillated celluloses from microalgal biomass using acid-free, TEMPO-free and bleach-free hydrothermal microwave processing is reported. Two routes were explored: i. direct microwave process of native microalgae (“standard”), and ii. scCO2 pre-treatment followed by microwave processing. ScCO2 was investigated as it is commonly used to extract lipids and generates considerable quantities of spent algal biomass. Defibrillation was evidenced in both cases to afford cellulosic strands, which progressively decreased in their width and length as the microwave processing temperature increased from 160 °C to 220 °C. Lower temperatures revealed aspect ratios similar to microfibrillated cellulose whilst at the highest temperature (220 °C), a mixture of microfibrillated cellulose and nanocrystals were evidenced. XRD studies showed similar patterns to cellulose I but also some unresolved peaks. The crystallinity index (CrI), determined by XRD, increased with increasing microwave processing temperature. The water holding capacity (WHC) of all materials was approximately 4.5 g H2O/g sample. The materials were able to form partially stable hydrogels, but only with those processed above 200 °C and at a concentration of 3 wt% in water. This unique work provides a new set of materials with potential applications in the packaging, food, pharmaceutical and cosmetic industries

Creation of Brønsted acid sites on Sn-based solid catalysts for the conversion of biomass

Hydroxyl-attached Sn species are highly dispersed on the surface of mesoporous silica (SBA-15) by the grafting of dimethyldichlorostannane followed by calcination to transform the methyl groups into hydroxyl groups (S–Sn–OH). S–Sn–OH has both Lewis and Brønsted acidic sites, resulting in superior catalytic activities in the acetalisation of glycerol

Valorisation of Citrus Fruit Peel Wastes and Blackcurrant Pomace via Acid-free Microwave Hydrothermal Processes

The chemical and allied-industries have been for too long reliant on crude oil and fossil fuels for their chemicals, materials and energy needs. These industries are significant contributors (approximately 4% of global CO2 emissions) to anthropogenic-induced global warming. Future thinking requires consideration of alternative, carbon-neutral renewable feedstocks, such as biomass, that develop biorefineries in place of traditional petroleum refineries. Unavoidable food supply chain wastes, such as citrus peels and blackcurrant pomace, are exemplars of large volume, renewable feedstock, which can be exploited (valorised) for the production of biobased chemicals, materials and bioenergy. Herein, the valorisation of citrus peels (orange and lemon) and blackcurrant pomace (BCP) via acid-free hydrothermal microwave processing, as opposed to conventional heating in acidic media, is reported. This valorisation approach formed two fractions: a hydrolysate which was rich in pectin (citrus) and antioxidants (BCP), and a solid fraction, giving microfibrillated cellulose (MFC) (citrus) and residues (BCP). Citrus pectin is linear polysaccharide with smooth region (homogalacturonan, HG) and hairy region (rhamno-galacturonan, RG). Orange pectin processed at 160 oC resulting in an RG-I pectin rich in galactan, which proved that hydrothermal microwave processing of orange pectin at 160 oC is a selective degradation. MFC was successfully characterised as a nanostructured material with properties highly dependent on the treatment temperature. BCP microwave hydrolysates (MHs) produced at low temperatures (<120 oC) were characterised as a complex mixture of variety compounds presenting antioxidant activity. In conclusion, the presented valorisation of citrus peels and BCP confirmed its potential as a valuable bioresource for the production of pectin, MFC and antioxidants with numerous potential applications

Insights into the Organotemplate-Free Synthesis of Zeolite Catalysts

As the most important nanoporous material, zeolites, which have intricate micropores, are essential heterogeneous catalysts in industrial processes. Zeolites are generally synthesized with organic templates under hydrothermal conditions; however, this method is environmentally unfriendly and costly due to the formation of harmful gases and polluted water. This article briefly summarizes the role of organic templates and describes designed routes for the organotemplate-free synthesis of zeolites, aided by zeolite seeds and zeolite seeds solution. Furthermore, this review explicates that the micropore volume decreases with an increase of the Si/Al ratios in the organotemplate-free synthesis of zeolite products, where Na+ exists as an alkali cation. This feature is very important in directing the synthesis of zeolite catalysts with controllable Si/Al ratios under organotemplate-free conditions, and is thus important for the efficient design of zeolites

Homochiral Porous Framework as a Platform for Durability Enhancement of Molecular Catalysts

Self-quenching and vulnerability of active sites are major issues posed for practical applications of highly efficient chiral organometallic catalysts. Here, we demonstrate an effective strategy to address these challenges by constructing them into homochiral porous frameworks, which renders them with extraordinary resistance against deactivation yet fully retains the intrinsic catalytic activities and selectivities under heterogeneous systems. Representatively, after partial metalation of the porous chiral phosphoramidite ligand-based frameworks (Phos-HPFs) with Rh species, the afforded catalysts exhibit dramatically enhanced durability while maintaining the activity and selectivity of the homogeneous counterparts in asymmetric hydrogenation of olefins. The rigid framework of Phos-HPFs can isolate the active sites, thus preventing the self-quenching from forming coordinatively saturated complexes, while the active sites surrounded by dense free chiral ligands in Phos-HPFs can inhibit them from decomposing into metallic particles. Our work thereby highlights the advantages of HPFs for the deployment of catalysts, which offers an opportunity for enhancing the utilization efficiency rather than merely having the benefits of easy separation and recycling of the chiral catalysts

Aluminum Fluoride Modified HZSM-5 Zeolite with Superior Performance in Synthesis of Dimethyl Ether from Methanol

A series of HZSM-5 catalysts modified with various loadings of aluminum fluoride (AlF₃) were prepared from a mechanical mixture route. Combined characterizations of X-ray diffraction, Fourier transform infrared (FT-IR), ²⁷Al, ²⁹Si, ¹⁹F MAS NMR, N₂ sorption, and NH₃-tempeature-programmed desorption (NH₃-TPD) techniques show that the structure, texture, and acidity of HZSM-5 catalysts can be adjusted with the loading of AlF₃. A suitable amount of AlF₃ modification (2 wt %) could increase the framework aluminum content and the surface area of HZSM-5. However, when the loading of AlF₃ came to 3 wt % or more, the contrary results were obtained, which could be ascribed to the dealumination of the zeolitic framework. The catalytic activities for dehydration of methanol to dimethyl ether (DME) show that suitable amount of AlF₃-modified HZSM-5 exhibited much higher activity and better stability than parent HZSM-5. The combination of “tunable” synthesis and “superior” properties is very much valuable in the academic and industry

Dataset for the submission in Estuarine, Coastal and Shelf Science YECSS-D-23-00597

&lt;p&gt;The data are saved as matlab data file.&lt;/p&gt;&lt;p&gt;1)&nbsp;ssc_fit.mat is used for producing figure 2.&lt;/p&gt;&lt;p&gt;2)&nbsp;Reynolds_shear_stress.mat&nbsp;is used for producing figures 3,&nbsp;5, 8 and 9.&lt;/p&gt;&lt;p&gt;3)&nbsp;hydrodynamics.mat&nbsp;is used for producing figure&nbsp;4.&lt;/p&gt;&lt;p&gt;4)&nbsp;shear_stress_&amp;_ssc.mat is uesd for producing figures 5 and 9.&lt;/p&gt;&lt;p&gt;5)&nbsp;SSF.mat&nbsp;is used for producing figures 6.&lt;/p&gt;&lt;p&gt;6)&nbsp;breaking_wave_criteria.mat&nbsp;is used for producing figure&nbsp;7.&lt;/p&gt;&lt;p&gt;&nbsp;&lt;/p&gt