Qing Ma

Layer structured graphite oxide as a novel adsorbent for humic acid removal from aqueous solution.

Layer structured graphite oxide (GO) was prepared from graphite using the Hummers-Offeman method, characterised using N(2) adsorption, XRD, XPS, SEM(TEM), and FT-IR, and tested for humic acid (HA) adsorption in aqueous solution. XRD, XPS, and FT-IR measurements indicate the formation of layered structure with strong functional groups of GO. It is also found that the GO exhibits strong and much higher adsorption capacity of HA than graphite. The maximum adsorption capacity of the GO from the Langmuir isotherm is 190 mg/g, higher than activated carbon. For the adsorption, several parameters will affect the adsorption such as solid loading and pH. HA adsorption will decrease with increasing pH and an optimum GO loading is required for maximum adsorption.

Influence of surface functionalization via chemical oxidation on the properties of carbon nanotubes

The surface of carbon nanotubes (CNTs) was functionalized in different chemical oxidants, hydrogen peroxide, mixed concentrated HNO(3)/H(2)SO(4) and acidic KMnO(4) solution. The influences on the properties of CNTs were systematically investigated, such as the structure, the kinds and the contents of the formed surface oxygen-containing functional groups, the pH(PZC) values and the surface hydrophilicity using XRD, HREM, FTIR and chemical titration. The results show that the kinds and the contents of the surface oxygen-containing groups are dependent on the functionalization methods. The formation of the oxygen-containing groups can decrease pH(PZC) values and improve surface hydrophilicity of CNTs. The dispersion of the supported Pd-Pt particles on the functionalized CNTs and their catalytic activity in the profile reaction of naphthalene hydrogenation to tetralin are both promoted due to the presence of these oxygen-containing groups.

Catalytic Conversion of Glucose to 5‐Hydroxymethyl‐furfural with a Phosphated TiO2 Catalyst

Nanosized phosphated TiO2 catalysts with different phosphate contents were synthesized and tested for the conversion of glucose to 5‐hydroxymethylfurfural. The resulting materials were characterized by using N2‐adsorption, XRD, inductively coupled plasma atomic emission spectroscopy, X‐ray spectroscopy, TEM, temperature‐programmed desorption of ammonia, and FTIR spectroscopy of pyridine adsorption techniques to determine their structural, bulk, surface, and acid properties. We found that TiO2 nanoparticles catalyzed this reaction under mild conditions in a water–butanol biphasic system. The incorporation of phosphorus into the TiO2 framework remarkably enhances the target product selectivity, which is ascribed to increased surface area, enhanced acidity, as well as thermal stability resulting from the Tiuf8ffOuf8ffP bond formation. Under optimal reaction conditions, phosphated TiO2 was found to exhibit excellent catalytic performance, which resulted in 97u2009% glucose conversion and 81u2009% HMF yield after 3u2005h of reaction at 175u2009°C. More importantly, the catalyst showed good stability and could be reused for several reaction cycles.

Direct Production of 5‐Hydroxymethylfurfural via Catalytic Conversion of Simple and Complex Sugars over Phosphated TiO2

A water-THF biphasic system containing N-methyl-2-pyrrolidone (NMP) was found to enable the efficient synthesis of 5-hydroxymethylfurfural (HMF) from a variety of sugars (simple to complex) using phosphated TiO2 as a catalyst. Fructose and glucose were selectively converted to HMF resulting in 98u2009% and 90u2009% yield, respectively, at 175u2009°C. Cellobiose and sucrose also gave rise to high HMF yields of 94u2009% and 98u2009%, respectively, at 180u2009°C. Other sugar variants such as starch (potato and rice) and cellulose were also investigated. The yields of HMF from starch (80-85u2009%) were high, whereas cellulose resulted in a modest yield of 33u2009%. Direct transformation of cellulose to HMF in significant yield (86u2009%) was assisted by mechanocatalytic depolymerization-ball milling of acid-impregnated cellulose. This effectively reduced cellulose crystallinity and particle size, forming soluble cello-oligomers; this is responsible for the enhanced substrate-catalytic sites contact and subsequent rate of HMF formation. During catalyst recyclability, P-TiO2 was observed to be reusable for four cycles without any loss in activity. We also investigated the conversion of the cello-oligomers to HMF in a continuous flow reactor. Good HMF yield (53u2009%) was achieved using a water-methyl isobutyl ketone+NMP biphasic system.

Guaiacol hydrodeoxygenation reaction catalyzed by highly dispersed, single layered MoS2/C

Highly disordered MoS2, dispersed on a carbon support was prepared by a microemulsion technique and its application as a catalyst for hydrodeoxygenation of guaiacol, a typical model compound of lignin, was investigated. The deoxygenation reaction was the predominant route, producing phenol as a major product. It is also demonstrated that the single layered MoS2/C catalyst showed superior activity and better deoxygenation and hydrogenation properties than the stacked MoS2/C catalyst. The reusability test showed good catalyst stability after 4 catalytic cycles were performed. Catalyst surface morphological changes, sulphur loss and its effect on conversion of guaiacol and selectivity to products were studied using multiple analytical methods such as TEM, XPS, CHNS, N2 adsorption and Raman analyses. The performance of the MoS2-based catalyst during guaiacol HDO reactions indicated its potential for upgrading of lignin.

High yield conversion of cellulosic biomass into 5-hydroxymethylfurfural and a study of the reaction kinetics of cellulose to HMF conversion in a biphasic system

Catalytic technology for cellulosic biomass conversion has been proven to be a promising approach for valuable chemical feedstock production. However, its recalcitrant nature is a major limitation to unlocking the carbohydrate biopolymer content and their subsequent conversion into 5-hydroxymethylfural (HMF). This paper investigates the production of HMF using glucose, cellulose, sugarcane bagasse and rice husk as the feedstocks. Acid dehydration of the carbohydrate sources was conducted in a biphasic system of water–MeTHF modified with N-methyl-2-pyrrolidone (NMP) over a phosphated TiO2 catalyst. The catalyst displayed a very good catalytic performance for the conversion of glucose into HMF (91% yield). More so, it is suitable for the selective conversion of mechanocatalytic depolymerized cellulose to 74.7% yield of HMF. Cellulosic biomass could also be directly converted into HMF and furfural in reasonable yields. The efficiency of biomass-to-HMF production was further advanced after biomass fractionation treatment. Remarkable yields of 72% and 65% HMF were produced from sugarcane bagasse and rice husk, respectively. Finally, the reaction kinetics of solubilized cellulose to HMF conversion was investigated and a simplified kinetic model comprising two reaction steps was developed: (1) hydrolysis of cello-oligomers to glucose and (2) glucose dehydration to HMF.

Dimensional Change Behavior of Caribbean Pine Using an Environmental Scanning Electron Microscope

Moisture transport and dimensional change during wood drying or wetting processes were analyzed based on pictures from an environmental scanning electron microscope (ESEM). This provides quantitative relationships between dimensional changes of total area, cell wall, and lumen, and moisture content for earlywood and latewood. Earlywood and latewood behave similarly but show some quantitative differences. The overall outcome for sections containing both kinds of wood seems to be dominated by the latewood behavior. The observed strain behavior of wood during drying is anisotropic in ways that are inconsistent with explanations solely related to microfibril orientation or earlywood/latewood interactions and more likely may be influenced by ray tracheids.

Influence of heat treatments on the pore and adsorption characteristics of sodium doped alumina pillared bentonite

Various amounts of Na+ ions were exchanged into alumina pillared bentonite (Al-PILB) sample, by controlling the pH of the dispersion of Al-PILB and sodium chloride solution. The Na+ doped pillared clays were calcined at elevated temperatures and adsorption of nitrogen at −196°C, cyclohexane and water at ambient temperature (21 ± 1°C) by the calcined samples were conducted. The results revealed a wide size distribution of the micropores in the pillared clay. Introduction of sodium ions converted the surface of the pore walls from hydrophobic to hydrophilic and blocks some micropores, enhancing water adsorption but reducing nitrogen and cyclohexane adsorption. Existence of Na+ ions in the pores did not improve the thermal stability of the pillared clay. Calcination at high temperatures resulted in a decrease in adsorption capacity. After calcination at 700°C, cyclohexane was inaccessible to the remaining micropores in the Na+ doped pillared clays. The adsorption behavior was clearly related to the cation content as well as the calcination temperature. These results may be useful in developing desiccants and adsorbents from pillared clays for dehumidification and adsorptive cooling applications.

Enabling Process Intensification by 3 D Printing of Catalytic Structures

Small‐scale, intensified chemical reactors (i.e., process intensification) mediated by structured catalysts substantially diminishes the advantages of large‐scale gas‐to‐liquid (transport fuels) process plants and can be realized at low capital costs, minimum energy consumption, and zero/small CO2 footprints. Current structured‐catalysts approaches are complex and expensive; therefore, simple methods are crucial that are capable of depositing a desired geometry of catalysts into engineered channels. Herein, we developed printable composition by incorporating nickel and molybdenum ions into water‐soluble PVA and starch; the subsequent pyrolysis of organic compounds resulted into three‐dimensional carbon scaffold with micro/macro interconnected pores (dpore, 6.5u2005Å; dpore, 100u2005μm) containing up to 25u2005wtu2009% catalyst loading. 2u2009D (TEM, SEM) and 3D (X‐ray computed tomography) microstructural analyses and catalytic tests (conversion of syngas to alcohols) were performed for 3u2009D printed catalysts and compared with conventional pelleted catalysts. At a high feed flow rate (6000u2005h−1), CO conversion is rapidly reduced to 16u2005molu2009% for pelleted catalysts, whereas 3u2009D printed catalysts converted 35u2005molu2009% of CO, with the same catalyst loading.