Survey of influence of biomass mineral matter in thermochemical conversion of short rotation willow coppice

Short rotation willow coppice (SRC) has been investigated for the influence of K, Ca, Mg, Fe and P on its pyrolysis and combustion behaviours. These metals are the typical components that appear in biomass. The willow sample was pretreated to remove salts and metals by hydrochloric acid, and this demineralised sample was impregnated with each individual metal at the same mol g biomass (2.4 × 10 mol g demineralised willow). Characterisation was performed using thermogravimetric analysis (TGA), and differential thermal analysis (DTA) for combustion. In pyrolysis, volatile fingerprints were measured by means of pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). The yields and distribution of pyrolysis products have been influenced by the presence of the catalysts. Most notably, both potassium and phosphorous strongly catalysed the pyrolysis, modifying both the yield and distribution of reaction products. Temperature programmed combustion TGA indicates that combustion of biomass char is catalysed by all the metals, while phosphorus strongly inhibits the char combustion. In this case, combustion rates follow the order for volatile release/combustion: P>K>Fe>Raw>HCl>Mg>Ca, and for char combustion K>Fe>raw>Ca-Mg>HCl>P. The samples impregnated with phosphorus and potassium were also studied for combustion under flame conditions, and the same trend was observed, i.e. both potassium and phosphorus catalyse the volatile release/combustion, while, in char combustion, potassium is a catalyst and phosphorus a strong inhibitor, i.e. K impregnated>(faster than) raw>demineralised»P impregnated.

Thermochemical characterisation of agricultural wastes from West Africa

Thermochemical characterisation of agricultural biomass wastes from West African region has been carried out and their potential use as feedstock in thermochemical conversion processes determined. Proximate, ultimate, structural compositions, calorific values, thermogravimetry (TGA) and derivative thermogravimetry (DTG) analyses were carried out on corn straw and cobs, rice straw and husks, cocoa pod, jatropha curcas and moringa olifiera seed cakes, parinari polyandra fruit shell and sugarcane bagasse. Moringa olifiera seed cakes and cocoa pods were found to contain the highest moisture contents. Rice straw was found to contain a high ash content of 45.76. wt.%. The level of nitrogen and sulphur in all the samples were very low. Rice husk was found to have the highest lignin contents while corn cob low lignin contents indicate a potential feedstock source for quality bio-oil production using thermochemical process. © 2013.

Intermediate pyrolysis studies of aquatic biomass and potential applications in the BtVB-process

Aquatic biomass is seen as one of the major feedstocks to overcome difficulties associated with 1st generation biofuels, such as competition with food production, change of land use and further environmental issues. Although, this finding is widely accepted only little work has been carried out to investigate thermo-chemical conversion of algal specimen to produce biofuels, power and heat. This work aims at contributing fundamental knowledge for thermo-chemical processing of aquatic biomass via intermediate pyrolysis. Therefore, it was necessary to install and commission an analytical pyrolysis apparatus which facilitates intermediate pyrolysis process conditions as well as subsequent separation and detection of pyrolysates (Py- GC/MS). In addition, a methodology was established to analyse aquatic biomass under intermediate conditions by Thermo-Gravimetric Analysis (TGA). Several microalgae (e.g. Chlamydomonas reinhardtii, Chlorella vulgaris) and macroalgae specimen (e.g. Fucus vesiculosus) from main algal divisions and various natural habitats (fresh and saline water, temperate and polar climates) were chosen and their thermal degradation under intermediate pyrolysis conditions was studied. In addition, it was of interest to examine the contribution of biochemical constituents of algal biomass onto the chemical compounds contained in pyrolysates. Therefore, lipid and protein fractions were extracted from microalgae biomass and analysed separately. Furthermore, investigations of residual algal materials obtained by extraction of high valuable compounds (e.g. lipids, proteins, enzymes) were included to evaluate their potential for intermediate pyrolysis processing. On basis of these thermal degradation studies, possible applications of algal biomass and from there derived materials in the Bio-thermal Valorisation of Biomass-process (BtVB-process) are presented. It was of interest to evaluate the combination of the production of high valuable products and bioenergy generation derived by micro- and macro algal biomass.

Novel pH‐and temperature‐responsive methacrylamide microgels

A novel transition temperature in MeAM copolymer microgels is reported. Despite the fact that MeAM homopolymers do not show thermosensitive properties, a specific synthetic strategy leads to a thermo-responsive swelling behavior that could be potentially useful in medical and/or industrial applications. The pH and temperature-dependent swelling response of microgels of MeAM copolymerized with 2-aminomethylpyridine and ethylenediamine is reported. The changes in particle sizes, which depend on the nature of the surrounding environment, are recorded by QELS. The relation between copolymer structure and its novel behavior is analyzed by several techniques (1H NMR, TGA).

Thermo-chemical behaviour and chemical product formation from Polar seaweeds during intermediate pyrolysis

Fundamental analytical pyrolysis studies of biomass from Polar seaweeds, which exhibit a different biomass composition than terrestrial and micro-algae biomass were performed via thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass-spectrometry (Py-GC/MS). The main reason for this study is the adaptation of these species to very harsh environments making them an interesting source for thermo-chemical processing for bioenergy generation and production of biochemicals via intermediate pyrolysis. Several macroalgal species from the Arctic region Kongsfjorden, Spitsbergen/Norway (Prasiola crispa, Monostroma arcticum, Polysiphonia arctica, Devaleraea ramentacea, Odonthalia dentata, Phycodrys rubens, Sphacelaria plumosa) and from the Antarctic peninsula, Potter Cove King George Island (Gigartina skottsbergii, Plocamium cartilagineum, Myriogramme manginii, Hymencladiopsis crustigena, Kallymenia antarctica) were investigated under intermediate pyrolysis conditions. TGA of the Polar seaweeds revealed three stages of degradation representing dehydration, devolatilization and decomposition of carbonaceous solids. The maximum degradation temperatures Prasiola crispa were observed within the range of 220-320 C and are lower than typically obtained by terrestrial biomass, due to divergent polysaccharide compositions. Biochar residues accounted for 33-46% and ash contents of 27-45% were obtained. Identification of volatile products by Py-GC/MS revealed a complexity of generated chemical compounds and significant differences between the species. A widespread occurrence of aromatics (toluene, styrene, phenol and 4-methylphenol), acids (acetic acid, benzoic acid alkyl ester derivatives, 2-propenoic acid esters and octadecanoic acid octyl esters) in pyrolysates was detected. Ubiquitous furan-derived products included furfural and 5-methyl-2-furaldehyde. As a pyran-derived compound maltol was obtained by one red algal species (P. rubens) and the monosaccharide d-allose was detected in pyrolysates in one green algal (P. crispa). Further unique chemicals detected were dianhydromannitol from brown algae and isosorbide from green algae biomass. In contrast, the anhydrosugar levoglucosan and the triterpene squalene was detected in a large number of pyrolysates analysed. © 2013 Elsevier B.V. All rights reserved.

The influence of harvest and storage on the properties of and fast pyrolysis products from Miscanthus x giganteus

The research investigates the fuel property variations associated with the time of harvest and the duration of storage of Miscanthus x giganteus over a one year period. The crop has been harvested at three different times: early (September 2009), conventional (April 2010) and late (June 2010). Once harvested the crop was baled and stored. Biomass properties of samples taken from different storage zones were compared. The thermochemical properties have been investigated using a range of analytical equipment including thermogravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). In addition, bio-oil has been produced from the early, conventional and late harvest using a laboratory scale (300gh) fast pyrolysis unit. The potential organic liquid yield (ondry basis, also excluding the reaction water generated) based on the laboratory fast pyrolysis processing undertaken in this study, was found to vary between 2.82 and 3.18 dry tha for the early and the late harvest respectively. The bio-oil organic yield was reduced by approximately 11% (0.36tha) between the early and the late harvest. Char yield was also reduced by approximately 18% (0.61tha). The highest gas yield (18.03%-1.60tha) was observed for the conventional harvest. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oil shows that levoglucosan, methylbenzaldehyde and 1,2-benzenediol all increase as a consequence of delayed harvest. It was also observed that by delaying the harvest time the O:C atomic ratio is reduced and a more carbonaceous feedstock is produced. © 2013 Elsevier Ltd.

Thermochemical characterisation of various biomass feedstock and bio-oil generated by fast pyrolysis

The projected decline in fossil fuel availability, environmental concerns, and security of supply attract increased interest in renewable energy derived from biomass. Fast pyrolysis is a possible thermochemical conversion route for the production of bio-oil, with promising advantages. The purpose of the experiments reported in this thesis was to extend our understanding of the fast pyrolysis process for straw, perennial grasses and hardwoods, and the implications of selective pyrolysis, crop harvest and storage on the thermal decomposition products. To this end, characterisation and laboratory-scale fast pyrolysis were conducted on the available feedstocks, and their products were compared. The variation in light and medium volatile decomposition products was investigated at different pyrolysis temperatures and heating rates, and a comparison of fast and slow pyrolysis products was conducted. Feedstocks from different harvests, storage durations and locations were characterised and compared in terms of their fuel and chemical properties. A range of analytical (e.g. Py-GC-MS and TGA) and processing equipment (0.3 kg/h and 1.0 kg/h fast pyrolysis reactors and 0.15 kg slow pyrolysis reactor) was used. Findings show that the high bio-oil and char heating value, and low water content of willow short rotation coppice (SRC) make this crop attractive for fast pyrolysis processing compared to the other investigated feedstocks in this project. From the analytical sequential investigation of willow SRC, it was found that the volatile product distribution can be tailored to achieve a better final product, by a variation of the heating rate and temperature. Time of harvest was most influential on the fuel properties of miscanthus; overall the late harvest produced the best fuel properties (high HHV, low moisture content, high volatile content, low ash content), and storage of the feedstock reduced the moisture and acid content.

Investigating the role of cholesterol in the formation of non-ionic surfactant based bilayer vesicles:thermal analysis and molecular dynamics

The aim of this research was to investigate the molecular interactions occurring in the formulation of non-ionic surfactant based vesicles composed monopalmitoyl glycerol (MPG), cholesterol (Chol) and dicetyl phosphate (DCP). In the formulation of these vesicles, the thermodynamic attributes and surfactant interactions based on molecular dynamics, Langmuir monolayer studies, differential scanning calorimetry (DSC), hot stage microscopy and thermogravimetric analysis (TGA) were investigated. Initially the melting points of the components individually, and combined at a 5:4:1 MPG:Chol:DCP weight ratio, were investigated; the results show that lower (90 C) than previously reported (120-140 C) temperatures could be adopted to produce molten surfactants for the production of niosomes. This was advantageous for surfactant stability; whilst TGA studies show that the individual components were stable to above 200 C, the 5:4:1 MPG:Chol:DCP mixture show ∼2% surfactant degradation at 140 C, compared to 0.01% was measured at 90 C. Niosomes formed at this lower temperature offered comparable characteristics to vesicles prepared using higher temperatures commonly reported in literature. In the formation of niosome vesicles, cholesterol also played a key role. Langmuir monolayer studies demonstrated that intercalation of cholesterol in the monolayer did not occur in the MPG:Chol:DCP (5:4:1 weight ratio) mixture. This suggests cholesterol may support bilayer assembly, with molecular simulation studies also demonstrating that vesicles cannot be built without the addition of cholesterol, with higher concentrations of cholesterol (5:4:1 vs 5:2:1, MPG:Chol:DCP) decreasing the time required for niosome assembly. © 2013 Elsevier B.V.

Potassium catalysis in the pyrolysis behaviour of short rotation willow coppice

Short rotation willow coppice (SRC) and a synthetic biomass, a mixture of the basic biomass components (cellulose, hemicellulose and lignin), have been investigated for the influence of potassium on their pyrolysis behaviours. The willow sample was pre-treated to remove salts and metals by hydrochloric acid, and this demineralised sample was impregnated with potassium. The same type of pre-treatment was applied to components of the synthetic biomass. Characterisation was performed using thermogravimetric analysis with measurement of products by means of Fourier transform infrared spectroscopy (TGA-FTIR) and pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). A comparison of product distributions and kinetics are reported. While the general features of decomposition of SRC are described well by an additive behaviour of the individual components, there are some differences in the magnitude of the influence of potassium, and on the products produced. For both SRC and the synthetic biomass, TGA traces indicate catalytic promotion of both of the two-stages of biomass decomposition, and potassium can lower the average apparent first-order activation energy for pyrolysis by up to 50 kJ/mol. For both SRC and synthetic biomass the yields and distribution of pyrolysis products have been influenced by the presence of the catalyst. Potassium catalysed pyrolysis increases the char yields markedly and this is more pronounced for synthetic biomass than SRC. Gas evolution profiles during pyrolysis show the same general features for both SRC and synthetic biomass. Relative methane yields increase during the char formation stage of pyrolysis of the potassium doped samples. The evolution profiles of acetic acid and formaldehyde change, and these products are seen in lower relative amounts for both the demineralised samples. A greater variation in pyrolysis products is observed from the treated SRC samples compared to the different synthetic biomass samples. Furthermore, substituted phenols from lignin pyrolysis are more dominant in the pyrolysis profiles of the synthetic biomass than of the SRC, implying that the extracted lignins used in the synthetic biomass yield a greater fraction of monomeric type species than the lignocellulosic cell wall material of SRC. For both types of samples, PY-GS-MS analyses show that potassium has a significant influence on cellulose decomposition markers, not just on the formation of levoglucosan, but also other species from the non-catalysed mechanism, such as 3,4-dihydroxy-3-cyclobutene-1,2-dione. © 2007 Elsevier Ltd. All rights reserved.

Evidence-based nanoscopic and molecular framework for excipient functionality in compressed orally disintegrating tablets

The work investigates the adhesive/cohesive molecular and physical interactions together with nanoscopic features of commonly used orally disintegrating tablet (ODT) excipients microcrystalline cellulose (MCC) and D-mannitol. This helps to elucidate the underlying physico-chemical and mechanical mechanisms responsible for powder densification and optimum product functionality. Atomic force microscopy (AFM) contact mode analysis was performed to measure nano-adhesion forces and surface energies between excipient-drug particles (6-10 different particles per each pair). Moreover, surface topography images (100 nm2-10 μm2) and roughness data were acquired from AFM tapping mode. AFM data were related to ODT macro/microscopic properties obtained from SEM, FTIR, XRD, thermal analysis using DSC and TGA, disintegration testing, Heckel and tabletability profiles. The study results showed a good association between the adhesive molecular and physical forces of paired particles and the resultant densification mechanisms responsible for mechanical strength of tablets. MCC micro roughness was 3 times that of D-mannitol which explains the high hardness of MCC ODTs due to mechanical interlocking. Hydrogen bonding between MCC particles could not be established from both AFM and FTIR solid state investigation. On the contrary, D-mannitol produced fragile ODTs due to fragmentation of surface crystallites during compression attained from its weak crystal structure. Furthermore, AFM analysis has shown the presence of extensive micro fibril structures inhabiting nano pores which further supports the use of MCC as a disintegrant. Overall, excipients (and model drugs) showed mechanistic behaviour on the nano/micro scale that could be related to the functionality of materials on the macro scale. © 2014 Al-khattawi et al.

Efficient alkyne homocoupling catalysed by copper immobilized on functionalized silica

Copper immobilized on a functionalized silica support is a good catalyst for the homocoupling of terminal alkynes. The so-called Glaser-Hay coupling reaction can be run in air with catalytic amounts of base. The copper catalyst is active for multiple substituted alkynes, in both polar and non-polar solvents, with good to excellent yields (75-95%). Depending on the alkyne, full conversion can be achieved within 3-24 h. The catalyst was characterized by TGA, inductively coupled plasma and X-ray photoelectron spectroscopy. Leaching tests confirm that the catalyst is and remains heterogeneous. Importantly, the overall reaction requires only alkyne and oxygen (in this case, air) as reagents, making this a clean catalytic oxidative coupling reaction. © 2012 John Wiley & Sons, Ltd.

Hierarchical nanoporous solid base catalysts for biofuels

Novel macroporous solid bases have been developed as alternative clean technologies to existing commercial homogeneous catalysts for the production of biodiesel from triglycerides; the latter suffer process disadvantages including complex separation and associated saponification and engine corrosion, and are unsuitable for continuous operation. To this end, tuneable macroporous MgAl hydrotalcites have been prepared by an alkali-free route and characterised by TGA, XRD, SEM and XPS. The macropore architecture improves diffusion of bulky triglyceride molecules to the active base sites, increasing activity. Lamellar and macroporous hydrotalcites will be compared for the transesterification of both model and plant oil feedstocks, and structure-reactivity relations identified.

Catalytic systems based on carbon fiber materials for the low-temperature oxidation of carbon monoxide

New heterogenized catalytic systems for the low-temperature oxidation of CO were synthesized by supporting solutions of Pd, Cu, and Fe salts on carbon fibrous materials (carbopon and busofit). The carbon supports were studied by elemental analysis, SEM, TGA, and TPD. The effects of the nature of the support, the concentration and composition of the active component, and the conditions of preparation on the efficiency of the catalytic system were studied. It was ascertained that attenuation of hydrophilic properties of the support led to the decrease in system activity. The investigation of the catalysts by XPS showed that sample treatment in the reaction medium results in redistribution of the components of the active phase in the near-surface layer of the catalyst. The catalytic system based on carbon fibrous material carbopon prepared by supporting active components (Pd, Cu, and Fe salts) in three stages with intermediate activation in the reaction medium ensures 95% conversion of CO under respiratory conditions, and is promising for the design of the main element of breathing masks on its basis.

Excipient characterization and particle engineering to develop directly compressed orally disintegrating tablets

ODTs have emerged as a novel oral dosage form with a potential to deliver a wide range of drug candidates to paediatric and geriatric patients. Compression of excipients offers a costeffective and translatable methodology for the manufacture of ODTs. Though, technical challenges prevail such as difficulty to achieve suitable tablet mechanical strength while ensuring rapid disintegration in the mouth, poor compressibility of preferred ODT diluent Dmannitol, and limited use for modified drug-release. The work investigates excipients’ functionality in ODTs and proposes new methodologies for enhancing material characteristics via process and particle engineering. It also aims to expand ODT applications for modified drug-release. Preformulation and formulation studies employed a plethora of techniques/tests including AFM, SEM, DSC, XRD, TGA, HSM, FTIR, hardness, disintegration time, friability, stress/strain and Heckel analysis. Tableting of D-mannitol and cellulosic excipients utilised various compression forces, material concentrations and grades. Engineered D-mannitol particles were made by spray drying mannitol with pore former NH4HCO3. Coated microparticles of model API omeprazole were prepared using water-based film forming polymers. The results of nanoscopic investigations elucidated the compression profiles of ODT excipients. Strong densification of MCC (Py is 625 MPa) occurs due to conglomeration of physicomechanical factors whereas D-mannitol fragments under pressure leading to poor compacts. Addition of cellulosic excipients (L-HPC and HPMC) and granular mannitol to powder mannitol was required to mechanically strengthen the dosage form (hardness >60 N, friability <1%) and to maintain rapid disintegration (<30 sec). Similarly, functionality was integrated into D-mannitol by fabrication of porous, yet, resilient particles which resulted in upto 150% increase in the hardness of compacts. The formulated particles provided resistance to fracture under pressure due to inherent elasticity while promoted tablet disintegration (50-77% reduction in disintegration time) due to porous nature. Additionally, coated microparticles provided an ODT-appropriate modified-release coating strategy by preventing drug (omeprazole) release.

Kinetic study of the pyrolysis of miscanthus and its acid hydrolysis residue by thermogravimetric analysis

The kinetic parameters of the pyrolysis of miscanthus and its acid hydrolysis residue (AHR) were determined using thermogravimetric analysis (TGA). The AHR was produced at the University of Limerick by treating miscanthus with 5 wt.% sulphuric acid at 175 °C as representative of a lignocellulosic acid hydrolysis product. For the TGA experiments, 3 to 6 g of sample, milled and sieved to a particle size below 250 μm, were placed in the TGA ceramic crucible. The experiments were carried out under non-isothermal conditions heating the samples from 50 to 900 °C at heating rates of 2.5, 5, 10, 17 and 25 °C/min. The activation energy (EA) of the decomposition process was determined from the TGA data by differential analysis (Friedman) and three isoconversional methods of integral analysis (Kissinger–Akahira–Sunose, Ozawa–Flynn–Wall, Vyazovkin). The activation energy ranged from 129 to 156 kJ/mol for miscanthus and from 200 to 376 kJ/mol for AHR increasing with increasing conversion. The reaction model was selected using the non-linear least squares method and the pre-exponential factor was calculated from the Arrhenius approximation. The results showed that the best fitting reaction model was the third order reaction for both feedstocks. The pre-exponential factor was in the range of 5.6 × 1010 to 3.9 × 10+ 13 min− 1 for miscanthus and 2.1 × 1016 to 7.7 × 1025 min− 1 for AHR.