PDF Publication Title:
Text from PDF Page: 004
4 | Clean Energy, 2017, Vol. XX, No. XX above-observed results [44, 49]. Bimbela et al. [44] reported that an increase in temperature from 550 to 650 °C over Ni-Al catalyst (28% wt. of nickel) boosted the hydrogen yield from 0.159G to 0.291G. A further increase in tempera- ture from 650 to 750 °C reduced the hydrogen yield slightly to 0.275G. Dhanala et al. [49] found that hydrogen yields were improved suddenly with increasing temperature to a maximum of between 630 and 696 °C depending on SCMR. The hydrogen yield then started declining slowly with fur- ther increase in temperatures. These observations are jus- tified by the following arguments: (1) SR reactions are favored at elevated temperature due to their endothermic nature, while exothermic WGS reac- tions are favored at lower temperature. At relatively lower temperature (below the temperature of maximum hydrogen yield), concentration of methane and butanol is high. So endothermic SR reactions dominate over exo- thermic WGS reaction at lower temperatures [49]. (2) The concentration of methane at a higher temperature decreases and endothermic rWGS reaction dominates over endothermic SR reactions leading to slight reduc- tion in hydrogen yields [49]. 1.2.2 Pressure There are very few studies which investigate the effect of pressure on SR of butanol. Roy et al. [22] studied the effect of pressure on SR of butanol over Ni (20% by wt.) supported on Al2O3 and CeO2 catalysts. With the increase in pressure, it was observed that conversion decreased and select- ivity to hydrogen increased. Maximum hydrogen select- ivity of 73%A and 45%A were obtained for Ni/CeO2 and Ni/ Al2O3 catalysts, respectively, during SR of butanol at 2099 kPa pressure. A decline in conversion was observed with increased pressure, as more active sites are available for butanol conversion at lower pressure. The probable reason for increased selectivity to hydrogen was the greater amount of water presence in the aqueous phase, which ul- timately improved activity of the WGS reaction [22]. During thermodynamic analysis of SR of butanol, Nahar et al. [42] reported that the increase in system pressure has a nega- tive impact on hydrogen yields. The highest documented hydrogen yield was ~62%C at 1 bar pressure and at 800 °C due to the high equilibrium constant the increased pres- sure had no effect on conversion. The decreased hydrogen yield was attributed to increased activity of methanation reactions due to the shift in equilibrium toward formation of methane with the increase in pressure [42]. 1.2.3 Steam to carbon molar ratio SCMR is considered as one of the most important parame- ters in SR reactions. Dhanala et al. [48] investigated the effect of SCMR on CCGP and hydrogen yields. It was documented that the hydrogen yield increased with increases in SCMR. The maximum hydrogen yield ~81%E was reported for SCMR of 3.2H. The same group of researchers in a different study [47] reported a similar trend for SCMR. An improved hydrogen yield from 73 to 90%C was documented with an increase in SCMR from 1.5H to 3.2H. Nahar et al. [42] studied the effect of water to butanol feed ratio. It was found that the increase in water to butanol feed ratio from 9 to 12 improved the hydrogen yield from 75.13 to 81.27%C. Hartley et al. [5] reported a similar trend over Ni and Rh supported on Al2O3 catalyst. Hydrogen yield increased from 51.3 to 58.3%F and from 42.6 to 45.3%F over Rh/Al2O3 and Ni/Al2O3 catalysts, respectively, by changing SBMR from 9J to 12J. In general, it is observed that an increase in steam content in feed improves hydrogen yields. This trend can be justi- fied by a shift in equilibrium in forward direction of SR and WGS reactions [47, 48]. However, higher SCMR increases endothermicity of the process. Therefore, while selecting optimum conditions for SR, a trade-off between hydrogen yields and heating requirements of SR process is needed. 1.2.4 Catalyst In SR, the catalyst plays a pivotal role in reactivity toward complete conversion, yield of specific product and sta- bility. Different catalysts induce different reaction path- ways, and therefore, the selection of a catalyst is of prime importance in SR of butanol. The catalyst should show higher selectivity toward hydrogen production, better re- sistance against coke formation and reduce production of unwanted by-products, i.e. CO. Hydrogen production by SR of butanol with different catalyst have been reported in several studies. The results and experimental conditions from the studies are summarized in Table 3. The tabulated results reveal that conversion and hydrogen yields depend on the type of metal, metal load- ing, preparation method, nature of support and the pres- ence of additives in the catalyst. Ni was found to exhibit better catalytic activity in terms of butanol conversion and hydrogen yields compared to Co and Mo over γ-Al2O3 sup- port [47]. The role of active metal is to activate butanol and promote its reaction with the hydroxyl group generated due to dissociation of water molecule on oxide support. For the same metal loading of Ni, Co and Mo, hydrogen chemisorption results revealed that Ni exhibited highest metal dispersion of 1.86% and active metal surface area of 12.4 m2/g of metal, which in turn resulted in better ac- tivity of the catalyst [47]. Hartley et al. [5] reported better hydrogen production capacity of Rh/Al2O3 in comparison to Ni/Al2O3. These results were justified by post-experiment analysis of the catalyst by temperature programmed oxi- dation (TPO) of catalysts, which revealed less coke depos- ition of 3.6 mmol coke/g of catalyst on Rh/Al2O3 compared to 6.0 mmol coke/g of catalyst on Ni/Al2O3 [5]. Support also plays a significant role in SR of butanol. It helps in dispersion of active metal by providing surface area. It may also enhance activity of catalyst by better sup- port–metal interaction. Dhanala et al. [47] investigated the effect of γ-Al2O3, SiO2 and ZrO2 as a support in SR of bu- tanol, using Ni as active metal. Ni supported on γ-Al2O3 showed higher catalytic activity compared to SiO2 and ZrO2. This behavior indicated that γ-Al2O3 showed better Downloaded from https://academic.oup.com/ce/advance-article-abstract/doi/10.1093/ce/zkx008/4743500 by guest on 15 December 2017PDF Image | Renewable hydrogen production from butanol
PDF Search Title:
Renewable hydrogen production from butanolOriginal File Name Searched:
Renewable_hydrogen_production_from_butanol.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |