Photoreduction of CO2 to fuels under sunlight using optical-fiber reactor 學 生 ： 周暐祥 報告日期： 98/10/16

Introduction When sunlight reaches the surface of the Earth, some of it is absorbed and warms the Earth. Some sunlight is utilized by green plants to produce hydrocarbons that constitute the world’s fossil fuel reserves, but it takes millions of years.

Introduction cont. For recent year, more and more fossil energy are consumed. When the fossil resource have been used, it release a lot of the CO2. And the fossil resource are not renewable.

Introduction cont. As we know, the CO2 is one of the greenhouse gas. For now a day, the temp. of the earth is going to increase more higher, and the climate is going to be changed. So finding the renewable resource is critical.

Introduction cont. Reducing the CO2 Removal of CO2 from Flue Gas in the Packed Tower by Ammonia Solution Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

Introduction cont. photocatalytic reduction of CO2 into fuels by using natural sunlight. Using sunlight recycle carbon dioxide and produce fuels like methanol or gasoline.

Photocatalytic conversion of CO2 into fuels reaction A continuous circular Pyrex glass reactor (216 cm3) with a quartz window for conduction of light irradiation.

Catalyst-coated optical fibers were inserted in the reactor. the light source enter along the fibers to conduct the photocatalytic reaction on its surface. The incident light is split to two beams when hitting the internal surface of fiber, due to the difference of refraction index between the TiO2 film and the fiber.

The UVA (320–500 nm) light was obtained by using an appropriate color filter. The temp. of the reactor maintain around 75 。 C. The reactor was purged by CO2 gas bubbling through distilled water for 1 h at 75 。 C before and during the reaction. The space velocity of CO2 gas and H2O vapor was maintained at 0.72 h1 for every experiment.

Results Bandgap energy of Cu (0.5 wt%)–Fe (0.5 wt%)/TiO2–SiO2–acac is substantially decreased to 1.55 eV, which is promising to absorb the full range of visible light.

The largest production rate of ethylene, mmol/g-cat h is observed on Cu(0.5 wt%)–Fe(0.5wt%)/TiO2 coated over optical fiber.

Conclusions The idea of recycling carbon dioxide is not new, but has generally been considered too difficult and expensive to be worth the effort. But with oil prices exceeding $100 per barrel and concerns about global warming mounting, researchers are increasingly motivated to investigate carbon recycling.

Conclusions cont. The advantage of photo-driven reaction is clearly benefited from the un-limited solar energy. An efficient photoreactor with high- photoactivity catalyst is essential step toward a commercial-scale application to produce renewable fuels.

References Photoreduction of CO2 to fuels under sunlight using optical-fiber reactor The-Vinh Nguyen1, Jeffrey C.S. Wu Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC Received 24 September 2007; received in revised form 10 January 2008; accepted 20 February 2008 Available online 18 April 2008 Scientists Use Sunlight to Make Fuel From CO2

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