Hideo Kameyama

Study of catalytic decomposition of formaldehyde on Pt/TiO2 alumite catalyst at ambient temperature.

Formaldehyde (HCHO) emitted from buildings, furnishing materials and consumer products is one of the most dominant volatile organic compounds (VOCs) in an indoor environment. In this work, a Pt/TiO(2)/Al(2)O(3) catalyst was prepared on an anodic alumite plate and was employed in the catalytic decomposition of formaldehyde at ambient temperature. Firstly, TiO(2) was deposited on the anodic alumite plate with electro-deposition technology. Then, platinum was supported on the anodic alumite plate with wet impregnation method. The developed catalyst exhibits good activity towards the decomposition of HCHO at ambient temperature. TPR (temperature programmed reduction) and TPD (temperature programmed desorption) analysis results indicate that oxygen adsorbed on the Pt/TiO(2)/Al(2)O(3) catalyst can be activated and generated to O:Pt(surface) species quickly at ambient temperature. Hence, the developed catalyst experiences the high activity towards the catalytic decomposition of formaldehyde at ambient temperature. Moreover, in accordance with the process requirements, the developed catalyst can be formed into various shapes such as a mesh, plate, fin, serrate etc., because aluminum can be formed into any shapes. The serrate type catalyst was prepared in this work and it also exhibits fine activity towards the decomposition of HCHO.

A simulation study of the UT-3 thermochemical hydrogen production process

Abstract A series of kinetic and simulation studies of four reactions consisting of the UT-3 cycle was made aiming at industrialization of this process. This cycle is given by 1 CaBr 2 (s)+H 2 O(g)→CaO(s)+2HBr(g) 2 CaO(s)+Br 2 (g)→CaBr(s)+1⧸20 2 (g) 3 Fe 3 O 4 (s)+8HBr(g)→3FeBr 2 (s)+4H 2 O(g)+Br 2 (g) 4 3FeBr 2 (s)+4H 2 O(g)→Fe 3 O 4 (s)+6HBr(g)+H 2 (g) This paper deals with rate expressions of these gas-solid reactions experimentally measured. Then, a simulation model for four fixed-bed reactors, in which four reactions are performed, and the calculation results are described. Also, the concept of process simulator is explained.

A proposal of a spray pulse operation for liquid film dehydrogenation: 2-Propanol dehydrogenation on a plate catalyst

Abstract This paper proposes a non-steady operation of a thin liquid film reactor for dehydrogenation of 2-propanol. The reactant 2-propanol is supplied as a spray pulse of a certain amount (1 to 1.5mmol) and at a certain interval (0.5 to 6s) on a Pt/Al 2 O 3 /Al catalyst kept at 368 K. The dehydrogenation reaction proceeds on the catalyst under thin reactant liquid film, and the produced hydrogen and acetone are released to the gas phase through the film immediately. Therefore, the products on the catalyst are kept at low concentrations. During one spray pulse of the reaction proceeds, the liquid film evaporates completely, which enables the regeneration of catalyst by releasing the adsorbed acetone, and the next spray pulse is supplied to the regenerated catalyst surface. This series of process achieved the reaction rate of 10 times as high as for the ordinary gas-phase steady operation. In this study, we used a plate catalyst support produced by anodic oxidation of aluminum, that has high heat conductivity. This is the key point to enable the non-steady operation by instant heat supply for the reaction and evaporation through the heat conductive catalyst kept at 368 K.

Development of catalytic combustion technology of VOC materials by anodic oxidation catalyst

Abstract The purpose of this study is to develop an anodic oxidation catalyst to be used as a VOCs removal catalyst. This catalyst consists of a porous alumina film formed on an aluminum plate or aluminum honeycomb and catalytic substances dispersed on the alumina. It therefore has many advantages over conventional catalysts such as: high thermal conductivity and easy to form into various shapes and structures. This paper presents the results of the optimization of the catalyst preparation and the bench scale test of these catalysts. The catalysts were prepared by anodic oxidation of a commercial aluminum plate or aluminum honeycomb monolith followed by the surface nano control process which is called hydration treatment. The characterization of the prepared catalysts was done in the term of pore size distribution and platinum content. The combustion activities were tested by using toluene combustion reaction as the model reaction. The results showed that the anodic oxidation catalysts pore size distribution profoundly affected the combustion activity. The catalyst with a bigger pore radius was feasible for this combustion system. We also succeeded in catalyzing an aluminum honeycomb monolith of serrated type and the test at the bench scale reactor showed that even at a very high space velocity of 90000 h−1 this catalyst performed better than the conventional one.

Economical and technical evaluation of UT-3 thermochemical hydrogen production process for an industrial scale plant

Abstract The thermochemical water-decomposition cycle UT-3 has been demonstrated with the successful operation of the bench-scale model plant. A commercial size UT-3 hydrogen generating plant was conceptually designed to assess the final hydrogen production cost. The encouraging results showed that the UT-3 cycle has the potential to become a competitive process for producing hydrogen.

Process simulation of MASCOT plant using the UT-3 thermochemical cycle for hydrogen production

Abstract A bench-scale plant named MASCOT for continuous hydrogen production based on the UT-3 cycle was constructed. Since then, a series of both theoretical and experimental studies aiming at industrialization of this plant have been conducted. This paper describes the modified process scheme of the plant as well as experimental results of fixed bed reactors. In addition, a two dimensional model of tubular reactor is proposed to simulate the reactor performance under the continuous operation.

Technical evaluation of UT-3 thermochemical hydrogen production process for an industrial scale plant

The continuous production of UT-3 thermochemical hydrogen has been successfully achieved through the operation of the bench-scale model plant. In parallel with this operation, a commercial size UT-3 hydrogen generating plant was conceptually designed to assess the process thermal efficiency. The applicability of the membrane gas separator has been evaluated for the case of applying a membrane separator to an Fe reactor in the UT-3 process. The encouraging results showed that the UT-3 process with the membrane separator has the potential to improve the process thermal efficiency and economical efficiency.

Design development of iron solid reactants in the UT-3 water decomposition cycle based on ceramic support materials

The UT-3 thermochemical water-decomposition cycle requires Fe reactant pellets with high reactivity and long life. Properties of Fe reactant pellets prepared using ZrO2-Y2O3, ZrSiO4 or SiO2 + ZrO2 as support materials were compared. The pellets with ZrO2-Y2O3 showed the highest density, hardness and content of Fe reactant, and kept a steady reactivity of 1.6–1.8 × 103 mol (Fe3O4) m−3 (pellet)−1 during 30 reaction cycles. The pellets with ZrSiO4 support were porous and showed high conversion.

Design of solid reactants and reaction kinetics concerning the iron compounds in the UT-3 thermochemical cycle

Abstract A preparation method has been studied for Fe compound reactant pellets, which are required to be highly reactive and durable to operate successfully in the UT-3 thermochemical water-decomposition process. Reactant pellets were prepared by calcination of a pelletized mixture of magnetite powder (reactant), inert ceramic particles of silica and zirconia powder (support substance) and such additives as cellulose and graphite powders (to give porosity). The reactant pellets were prepared by adding both graphite and zirconia powders into the raw materials until the pellets showed the highest reactivity and durability. It was shown that the pore volume of pellets increased linearly from 0.07 to 0.35 ml g −1 with the graphite content in the raw material mixtures, and that pellets prepared with 20 wt% graphite were five times as reactive as those prepared without graphite. Kinetics measurements were made for bromination of hematite and magnetite, and hydrolysis of iron bromide.

Development of a Microreactor with a Structured Catalyst

A novel microreactor with a structured catalyst was proposed. The structured catalyst has micro partition (MP), which functions as a catalyst support. The MP has fins on the plate with holes and consists of aluminum, and it was loaded into the tube. To demonstrate the influence of MP on reactivity, the methanol conversion for steam reforming was measured. First, the methanol conversion of the MP and MP with flatten fins on the surface (i.e., plate-like structure) catalysts were compared. The MP-structured catalyst demonstrated higher reactivity for methanol than the conventional plate-like catalyst. It was also shown that direction of fins must be taken into account for improving the reactivity. The influence of MP on reaction rate constant was analyzed and compared with the plate-type catalyst. Moreover, a simulation was carried out to determine the steady-state flow behavior. It was found that the streamlines went through the holes only when the holes were aligned behind the fins against the stream. This behavior corresponded with the experimental result that directions of fins are important for improving the reactivity