Biomass-derived sugars have attracted increasing attention in recent years as an alternative carbon source. Although significant advances have been reported in the development of catalysts for the conversion of carbohydrates into key chemicals, only a limited range of products can be obtained. We herein describe the highly-selective syntheses of a range of useful compounds using biomass-derived sugars. Firstly, we focused on the upgrade of 1,3-dihydroxyacetone (DHA) generated from glucose to yield useful compounds. Additionally, we achieved the utilization of algal residue as a new carbon resource to produce important chemicals. The establishment of this novel synthetic methodology to generate valuable chemical products from saccharides renders carbohydrates a potential alternative carbon resource to fossil fuels.
Hydroxymethylfurfural (HMF) is a platform compound that can be derived from cellulose for coming biomass society. It is known that the formation of HMF from cellulose is a three-step reaction: (1) hydrolysis of cellulose into glucose, (2) glucose isomerization to fructose and (3) fructose dehydration to HMF. Reactions 1 and 3 are acid-catayzed and reaction 2 is base-catalyzed. To increase the yield of HMF, optimization of each reaction step is necessary. To develop a total process for conversion of cellulose into HMF step 2 (glucose isomerization) was optimized in the presence of water and the effect of water on step 3 was investigated. For isomerization of glucose in the presence of 35 wt% of water in [BmIm]Cl, magnesium carbonate was the most effective base additive (23.1 mol% fructose yield with 85.3 mol% selectivity) for reaction conditions of 120 °C for 30 min reaction time. For dehydration of fructose into HMF with Amberlyst 15, the rate of dehydration of fructose was reduced by adding water and the existence of glucose was negligible for the rate of dehydration of fructose. Finally, continuous HMF production process via three-step reaction is proposed and the yield of HMF from cellulose is estimated to be 32 mol%.
Based on the principle of nitrogen gas stripping for the residual methanol removal from crude biodiesel fuel (BDF) that we reported previously (Yamane et al., Eur. J. Lipid Sci. Technol., 115, 1183-1192 (2013)), two scaled gas stripping setups whose working volume were 5 L and 25 L were constructed to study its scale-up. As a scale-up index, (flow rate of nitrogen gas)/(volume of crude BDF), Q/V, gave the best correlation among the three indices, i.e. Q/V, Pg/V (= energy consumption of gas pump for gas stripping)/(volume of crude BDF), and u (= linear gas velocity = Q/(cross-sectional area)). The three items, i.e. Pa, Pg, and Pb, composed of the total energy consumption, Ptotal, of the two gas stripping setups were measured. Ptotal/V was approximately 0.1 [kWh/L] when Q/V was 1.5 [1/min] in 25 L-scaled gas stripping setup. As the simplest as well as inexpensive purification process, the purification process composed of the intensive residual methanol removal by a nitrogen gas stripping system followed by filtration with aid of appropriate filter aid was proposed.
We tried to obtain practical data on bulk density of forest residues for truck transportation in order to apply it to woody biomass electric power generation. A case study of packing and transportation using a panel truck of 11.5 t capacity was conducted for three types of forest residues: logs, twigs, and their mixture, with two repetitions for each. Bulk density was measured from bulk volume of residues and weight of the loads. The achieved packing efficiency ranged from 0.50 to 0.95. Using the data, we estimated the loading weight with packing efficiency of 1.00 to be 15.25 t, 5.78 t, 11.46 t for logs, twigs, and the mixture, respectively. A series of numerical examination found that in order to achieve the maximum loading weight of 11.5 t, keeping packing efficiency of 1.00, mixture of logs and twigs would be the best method with the ratio of twigs to be around 0.4 to 0.5.
To investigate the reaction cross section of the cesium exchange reaction of 133CsI (v = 0, j = 0) + 135Cs → 133Cs + I135Cs, we performed quasi-classical trajectory calculations. The potential energy surface was constructed at the ab initio MP2/def2-QZVPPD level. The potential energy surface calculated implies that the title reaction is barrierless and that the Cs2I intermediate, whose two Cs-I bonds are chemically equivalent, is easily formed. The reaction cross sections decrease monotonically with increasing collision energy. The rate constant k (v = 0, j = 0) was estimated to be about 3 × 10-10 cm3 molecule-1 s-1 at temperatures ranging from 500 to 1200 K and a slight negative temperature dependence was observed.
Thermocatalytic decomposition of methane (TCD) is a promising method for producing hydrogen. However, the main concerns of this process are very high reaction temperature and fast deactivation of the catalyst. In this work, a positive approach has been made to minimize both effects by using Pd-promoted catalyst prepared by the co-precipitation and impregnation method. Pd has a high affiliation with carbon, thus instead of encapsulating Ni, it diffuses in promoter hence the catalytic lifetime is prolonged. EDX and XRD analysis confirmed the presence of NiAl2O4, Al2O3, Pd, and Ni. BET analysis depicts that the surface area is decreased as the amount of metal content impregnated on the support is increased. FESEM analysis shows the nano particles are synthesized while carbon nanofibers are produced as by-product. The highest conversion of CH4 was given by Cat 1 (24.7 wt%Ni-0.3 wt%Pd/Al2O3) i.e. 45%.
There is an imperative need to explore new technologies for hydrogen energy production without sacrificing life and environment. A 27.12 MHz radio-frequency plasma in liquid was used to decompose cellulose suspension for hydrogen production. The experiment was conducted to investigate the effects of sodium hydroxide and ultrasonic irradiation pretreatment. Molar concentration of sodium hydroxide was varied to 0.001 M, 0.01 M and 0.1 M and ultrasonic irradiation time was varied between 15 and 60 minutes in order to observe the hydrogen production rate and hydrogen yield. Hydrogen production had no significant enhancement at lower than 0.01 M sodium hydroxide. On the other hand, the hydrogen production rate increased dramatically to 23.0 µmol/s at 0.1 M sodium hydroxide. Typical optical emission spectrum of 0.001 M sodium hydroxide solution showed that radical species including OH (281.1 nm), Hβ (486 nm), Hα (656.3 nm) and O (777 and 845 nm) were generated which are very beneficial in attacking and decomposing organic molecules for hydrogen production. The highest production rate was obtained at 30 minutes of pretreatment. A longer than 30 minutes pretreatment with ultrasonic irradiation reduced the hydrogen production rate. Thus, ultrasonic irradiation pretreatment between 15 and 30 minutes was the potential condition for hydrogen production without sacrificing greenhouse gases effect.
The demand for energy and its resources is increasing daily due to the rapid outgrowth of population and urbanisation. Petroleum is a non-regenerate source of energy. The increasing price of petroleum and environment concerns making the search for alternative renewable fuels is gaining considerable attention. Biodiesel is among the most promising alternative fuel to replace petroleum-based diesel. In this work, biodiesel was produced via transesterification of palm oil with methanol in the presence of heterogeneous catalyst alkaline based clay KOH/MK-10. The surface and structural properties were measured via latest techniques of SEM and BET surface analysis. The characterisation of prepared catalyst showed that surface area and pore volume of modified clay decreased but the morphology of clay was observed as the same after potassium modification. The results showed that prepared KOH/MK-10 is highly active for transesterification reaction under optimized condition. The maximum conversion of triglyceride was noted 98% after 3 h of reaction at 60 °C with a 15:1 molar ratio of methanol to palm oil and 3 wt % of the prepared catalyst.
This study was undertaken to analyze the photovoltaic generation potential of agricultural areas in Yamanashi Prefecture. An important issue in agricultural areas is the effective utilization of abandoned farmland. For example, solar sharing systems have made it possible to produce food and renewable energy on the same land simultaneously. The author proposed a method for assessing introduction potential of abandoned farmlands using geographical information systems. Agricultural settlements became classifiable into 1,687 irregular land areas based on census of agriculture and forestry. The author divided Yamanashi into 4,500 areas by the grid square data in more detail. This study investigated the use of overlay analysis to find south-facing slopes with 20 degree maximum inclination angle. In addition, the photovoltaic generation potential amount was estimated, excluding natural park areas and natural conservation areas. The photovoltaic generation potential in Yamanashi was estimated as 998 GWh per year using the amount of global solar radiation. The author extracted 215 grid square data using sensitivity analysis of the distance from transmission lines to the abandoned farmlands. Results revealed electric power generation of the areas as 394 GWh annually: equivalent to 6.4% of the electrical power consumption of Yamanashi Prefecture in FY2014.
As an example of utilizing Australian Brown coal, a conceptual study is conducted for a system based on DME which is clean and easily transferrable fuel. CO2 will be emitted when DME is produced from reduced gas by a gasification of Brown coal. Compared to the base case in which CO2 is only treated by CCS, it is clarified that the amount of generated DME may be increased and the capacity of CCS can be largely reduced by introducing renewable hydrogen. Renewable hydrogen could be produced by electrolysis of water using electric power generated by wind power. This means that it will be one of the solutions in a case of utilizing coal resources when CCS is technically and socially restricted, DME is transported from Australia to Japan where DME is used for a power generation. As the result of the study, it is clarified that CO2 emitted from a DME fired power station is the same level as that from LNG fired. Therefore, it is possible to largely reduce CO2 emissions compared to that from the conventional coal fired ones.
Widespread of fuel-cell vehicles (FCV) is one of the essential solutions to CO2 emission mitigation. However there were only 81 working hydrogen stations distributed in Japan in January 2017. Therefore, it has become increasingly necessary to establish the hydrogen stations. In this study, we focus on the unutilized hydrogen production capacity of a fuel processor system (FPS) incorporated in a residential fuel cell co-generation system. We proposed a system which the FPS and fuel cell stacks are operated independently at their respective efficient load factors, and which can produce hydrogen for the FCV using the unutilized capabilities of the FPS. An optimum scheduling model for the operation of the FPS and the fuel cell stacks was developed to evaluate annual hydrogen production for the FCV for 24 households. As the results, it was found that all households have the capacity to produce at least 1,040 Nm3/year of hydrogen, which a FCV can run 8,000 km in a year. Furthermore, we evaluated the hydrogen supply potential of collective housings installed this system to each household through the case study in Tama region, Tokyo. In the case where this system was introduced to 10 collective housings in Tama region, it was found that 80.9% of hydrogen demand for FCV in this region in 2025 in this region could be supplied.