NOVEL SOLAR ENERGY CONVERSION SYSTEM USING WATER AND SULFUR

本年度以实现太阳能转换系统（SECS）为目标，集中进行了以下课题的研究：1.高效光催化剂的开发--本年度成功地扩大了去年开发的光催化剂合成工序，获得了高效SECS所需的CdS粒子的量。因此，本年度的研究重点是开发一种以溶解在碱性溶液中的硫化氢（H_2S）为原料，并有效分离氢气的光催化电池。2.反应过程中副产物的去除-当H_2S被光分解时，除了氢气外，还产生了阻碍反应的硫簇（SC）。因此，开发了基于电子转移特性的物理分离过程，以回收SC而不降解系统中的反应物。在该过程中，富勒烯（C_<60>），其在高碱性条件下稳定分散，被用作 ...更多信息 n电子供体。当将富勒烯引入分散SC的黄色悬浮液中时，悬浮液瞬间变成无色。此外，将通过对含硫富勒烯进行热处理而回收的硫（S）用于制备原料，以生产H_2S。3.从回收的硫再生硫化氢去年以前，曾尝试在水热条件下用水处理硫，使硫循环，但今年尝试了利用硫酸盐还原菌（SRB）再生H_2S。4.硫化氢的富集由于硫酸盐还原菌处理硫磺产生的H_2S伴随着大量的甲烷和二氧化碳，开发了基于固体和液体吸收剂的富集技术，获得接近100%的H_2。2.完成了太阳能转换系统的研制。少

This year, we concentrated our research on the following topics aiming the accomplishment of solar energy conversion system (SECS)1.Development of highly efficient photocatalyst-This year, we succeeded in scaling up the photocatalyst synthesis process (developed last year) to obtain necessary quantity of CdS particles for efficient SECS. As a consequence, this year' s research was focused on the development of a photocatalytic cell that utilizes hydrogen sulfide (H_2S) dissolved in alkaline solution as raw material and separate the hydrogen evolved effectively.2.Removal of by-products evolved during reaction-When H_2S is photosplit, besides hydrogen, sulfur clusters (SC), which hinders the reaction is also produced as a by-product. Thus, a physical separation process based on electron transfer characteristics was developed to recover SC without degrading the reactants in the system. In this process, fullerene (C_<60>), which stably disperses in highly alkaline conditions, was used as a … More n electron donor. When fullerene was introduced into the yellow colored suspension dispersing SC, the suspension turned colorless instantaneously. Furthermore, sulfur (S) recovered by heat-treating sulfur-contained fullerene was used for the preparation of the raw material to produce H_2S.3.Reproduction of hydrogen sulfide from recovered sulfurThough circulation of sulfur was attempted by treating the same with water under hydrothermal conditions until last year, reproduction of H_2S using sulfate reducing bacteria (SRB) was attempted this year. As a result, we succeeded in the production of biogas containing 15 % of H_2S, which is equivalent to methane fermentation.4.Enrichment of hydrogen sulfideSince the H_2S produced by treating sulfur with SRB is associated with large quantities of methane and carbon dioxide, solid and liquid absorbents based enrichment technology was developed to obtain nearly 100 % H_2S.Solar energy conversion system was accomplished by carrying out the above researches. Less