Production of glucose from the acid hydrolysis of anhydrosugars

Acid hydrolysis of levoglucosan and cellobiose as anhydrosugar model compounds was carried out in an autoclave Parr reaction system, using sulphuric acid as catalyst. In addition, acid hydrolysis was carried out using an anhydrosugars mixture from the aqueous fraction of a pyrolysis oil or bio-oil. The bio-oil was obtained from the fast pyrolysis of birch-wood, and the segregated aqueous fraction was found to contain mainly levoglucosan with a concentration of 30 g L-1. Three main hydrolysis parameters including temperature, reaction time, and catalyst to substrate ratios were varied in order to identify their influence towards glucose production. It was found that at hydrolysis conditions of 120 °C, 60 minutes, and a catalyst/substrate ratio of 0.9; glucose yields of 98.55% and 96.56%, and conversion of substrates of 100% and ~92%, were achieved when hydrolysing cellobiose and levoglucosan respectively. An increase in the hydrolysis temperature from 120 °C to 135 °C, resulted in a decrease in the glucose yield and selectivity. Whereas high conversions of substrates (~90%) were maintained for both anhydrosugars. This was attributed to the further dehydration reactions of glucose, possibly yielding HMF or levulinic acid. During the acid hydrolysis of the bio-oil aqueous fraction, a range of hydrolysis conditions suitable to achieve glucose yields higher than 90%, was depicted. It was found that catalyst/substrate molar ratios between 0.17-0.90 and temperatures between 118 °C and 126 °C were suitable conditions to achieve glucose yields ~100% (30 g L-1). Furthermore, glucose concentrations ~117% (35 g L-1) and levoglucosan conversions above 90%, were attained at 135 °C, 20 minutes reaction time and at an estimated catalyst/substrate molar ratio of 0.2 (H2SO4, 0.5 M)

Characterisation and Py-GC/MS analysis of Imperata Cylindrica as potential biomass for bio-oil production in Brunei Darussalam

Bio-oil production from renewable sources has been seen as suitable alternative to supply future energy demand. Perennials grasses are currently being developed as a suitable second-generation biofuel feedstock. It has advantages such as rapid growth rate, easy to grow, minimal maintenance and utilise marginal land without competing with food supply. Taking into account of the various challenges attributed to the transformation of second-generation biomass for energy production, this work systematically looks at the ecological perspective and the availability for bioenergy production from Imperata Cylindrica in Brunei Darussalam. Biomass characterisation was carried out to determine the properties and energy content, meanwhile py-GC/MS study was conducted to identify building blocks of value-added chemical from I. cylindrica. The physicochemical properties of feedstock was thoroughly evaluated using thermogravimetric analysis, proximate analysis, elemental analysis, compositional analysis, calorific value, and analytical pyrolysis interfaced with gas chromatograph (Py-GC/MS). Characterisation results indicate that Imperata Cylindrica has a calorific value of 18.39 MJ/kg, with low ash content and high percentage of volatile matter. Py-GC/MS analysis revealed the presence of furfural, 2,3-dihydrobenzofuran, 4-vinylguaiacol, propenylguaiacol, guaiacol and 4-ethylphenol. The fixed-bed pyrolysis experiment of imperata cylindrica showed that the yield of bio-oil increases with the increase of temperature and it reached a peak of 37.16% at 500 °C. These results show that Imperata Cylindrica is suitable as feedstock for bio-oil production via pyrolysis process

Potential of Virginia Mallow as an Energy Feedstock

This study aims to compare the potential of Virginia mallow to other high yielding perennial grasses and hardwoods by characterising and comparing fast pyrolysis product yields. Feedstocks selected for this study include miscanthus (Miscanthus x giganteus), Virginia mallow (Sida hermaphrodita), willow short rotation coppice (SRC) (Salix viminalis) and oak (Quercus robur). The experimental work was split into two sections: analytical (Py–GC–MS) and laboratory-scale processing using a 300 g h−1 continuous bubbling fluidised bed reactor. Pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) has been used to quantify pyrolysis products from these feedstocks by simulating fast pyrolysis heating rates using a CDS 5200 pyrolyser closed coupled to a PerkinElmer Clarus 680 GC–MS. High bio-oil yields were achieved for Virginia mallow, willow SRC and oak (65.36, 62.55 and 66.43 wt% respectively), but miscanthus only produced a yield of 53.46 wt% due to increased feedstock ash content. The water content in the bio-oil is highest from miscanthus (17.64 wt%) and relatively low in the Virginia mallow and hardwoods willow SRC and oak (12.49, 13.88 and 14.53 wt%). Similar high yields of bio-oil and low yields of char and non-condensable gas compared to willow SRC make Virginia mallow an attractive feedstock for fast pyrolysis processing. Graphic Abstract: [Figure not available: see fulltext.]

Robotic Thumb Assembly

An improved robotic thumb for a robotic hand assembly is provided. According to one aspect of the disclosure, improved tendon routing in the robotic thumb provides control of four degrees of freedom with only five tendons. According to another aspect of the disclosure, one of the five degrees of freedom of a human thumb is replaced in the robotic thumb with a permanent twist in the shape of a phalange. According to yet another aspect of the disclosure, a position sensor includes a magnet having two portions shaped as circle segments with different center points. The magnet provides a linearized output from a Hall effect sensor

Signatures of granular microstructure in dense shear flows

Granular materials react to shear stresses differently than do ordinary fluids. Rather than deforming uniformly, materials such as dry sand or cohesionless powders develop shear bands: narrow zones containing large relative particle motion leaving adjacent regions essentially rigid[1,2,3,4,5]. Since shear bands mark areas of flow, material failure and energy dissipation, they play a crucial role for many industrial, civil engineering and geophysical processes[6]. They also appear in related contexts, such as in lubricating fluids confined to ultra-thin molecular layers[7]. Detailed information on motion within a shear band in a three-dimensional geometry, including the degree of particle rotation and inter-particle slip, is lacking. Similarly, only little is known about how properties of the individual grains - their microstructure - affect movement in densely packed material[5]. Combining magnetic resonance imaging, x-ray tomography, and high-speed video particle tracking, we obtain the local steady-state particle velocity, rotation and packing density for shear flow in a three-dimensional Couette geometry. We find that key characteristics of the granular microstructure determine the shape of the velocity profile.Comment: 5 pages, incl. 4 figure

Slow pyrolysis of organic fraction of municipal solid waste (OFMSW): Characterisation of products and screening of the aqueous liquid product for anaerobic digestion

A comprehensive study of the energy yield from slow pyrolysis of the organic fraction of municipal solid waste (OFMSW) and energy recovery from the aqueous liquid product by anaerobic digestion has been carried out. In this paper, the results of the liquid pyrolysis product characterisation are presented, with toxicity and methane potential assessments of the aqueous liquid product. The OFMSW feedstock was obtained from a UK waste treatment plant. Shredded samples dried to different moisture contents (12.7–45.8%) were processed in a 300 g per hour auger screw pyrolysis reactor at temperatures from 450 to 850 °C. Sixteen pyrolysis runs were performed, with process mass balance closures above 90% obtained (wet feed basis). Pyrolysis liquids showed clear phase separation under gravity. With increasing processing temperature, the liquid yield (both organic and aqueous fraction) reduced but the gas yield increased. An investigation into the product energy distribution indicated that processing temperature had a strong effect on the product energy distribution, while the effect of feedstock moisture was relatively small. Batch anaerobic testing of the aqueous fraction showed that toxicity increased with pyrolysis processing temperature and decreased with feedstock moisture content. Statistical analysis confirmed that the pyrolysis processing temperature was the dominant factor affecting the toxicity of the aqueous product. Careful acclimatisation of the microbial consortium to the applied substrate and loading is likely to be necessary for improved digestion of the aqueous fraction

Viscosity of aged bio-oils from fast pyrolysis of beech wood and miscanthus:shear rate and temperature dependence

The viscosity of four aged bio-oil samples was measured experimentally at various shear rates and temperatures using a rotational viscometer. The experimental bio-oils were derived from fast pyrolysis of beech wood at 450, 500, and 550 °C and Miscanthus at 500 °C (in this work, they were named as BW1, BW2, BW3, and MXG) in a bubbling fluidized bed reactor. The viscosity of all bio-oils was kept constant at various shear rates at the same temperature, which indicated that they were Newtonian fluids. The viscosity of bio-oils was strongly dependent upon the temperature, and with the increase of the temperature from 30 to 80 °C, the viscosity of BW1, BW2, BW3, and MXG decreased by 90.7, 93.3, 92.6, and 90.2%, respectively. The Arrhenius viscosity model, which has been commonly used to represent the temperature dependence of the viscosity of many fluids, did not fit the viscosity-temperature experimental data of all bio-oils very well, especially in the low- and high-temperature regions. For comparison, the Williams-Landel-Ferry (WLF) model was also used. The results showed that the WLF model gave a very good description of the viscosity-temperature relationship of each bio-oil with very small residuals and the BW3 bio-oil had the strongest viscosity-temperature dependence

Centaur: NASA’s mobile humanoid designed for filed work

Abstract -NASA's future lunar and martian missions will require a suite of advanced robotic systems to complete tasks during precursor visits and to assist humans while present on the surface. The Centaur is a new mobile, dexterous manipulation system designed with this future role in mind. Centaur combines the sophisticated upper body dexterity of NASA's humanoid, Robonaut, with a rugged and versatile four-wheeled base. This combination allows for robotic use of human tools and interfaces in remote locations by incorporating design improvements to the existing Robonaut that target the challenges of planetary field work: rough terrain, a varied environment (temperature, dust, wind, etc.), and distance from human operators. An overview of Centaur's design is presented focusing on the features that serve to mitigate the above risks and allow the robot to perform human-like tasks in unstructured environments. The success of this design is also demonstrated by the results of a recent coordinated field demonstration in which Centaur, under both teleoperated and autonomous control, cooperated with other NASA robots

Catalytic pyrolysis of rice husk for bio-oil production

Catalytic pyrolysis experiments have been carried out on Brunei rice husk (BRH) to obtain bio-oil using a fixed-bed pyrolysis rig. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) were used as the catalysts for the catalytic pyrolysis experiments and comparison was done to analyse the changes in the bio-oil properties and yield. Properties of the liquid catalytic and non-catalytic bio-oil were analysed in terms of water content, pH, acid number, viscosity, density and calorific value. The bio-oil chemical composition shows that ZSM-5 increases the production of aromatic hydrocarbons and light phenols, whilst Al-MCM-41 reduces the acetic acid production. The catalytic runs increased the calorific value and water content in the bio-oil, whilst viscosity, density and acid number is decreased

Shearing of loose granular materials: A statistical mesoscopic model

A two-dimensional lattice model for the formation and evolution of shear bands in granular media is proposed. Each lattice site is assigned a random variable which reflects the local density. At every time step, the strain is localized along a single shear-band which is a spanning path on the lattice chosen through an extremum condition. The dynamics consists of randomly changing the `density' of the sites only along the shear band, and then repeating the procedure of locating the extremal path and changing it. Starting from an initially uncorrelated density field, it is found that this dynamics leads to a slow compaction along with a non-trivial patterning of the system, with high density regions forming which shelter long-lived low-density valleys. Further, as a result of these large density fluctuations, the shear band which was initially equally likely to be found anywhere on the lattice, gets progressively trapped for longer and longer periods of time. This state is however meta-stable, and the system continues to evolve slowly in a manner reminiscent of glassy dynamics. Several quantities have been studied numerically which support this picture and elucidate the unusual system-size effects at play.Comment: 11 pages, 15 figures revtex, submitted to PRE, See also: cond-mat/020921