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首页> 外文学位 >In situ infrared study of adsorbed species during catalytic oxidation and carbon dioxide adsorption.
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In situ infrared study of adsorbed species during catalytic oxidation and carbon dioxide adsorption.

机译：催化氧化和二氧化碳吸附过程中吸附物质的原位红外研究。

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Hydrogen is considered to be the fuel of the next century. Hydrogen can be produced by either water splitting using the solar or nuclear energy or by catalytic cracking and reforming of the fossil fuels. The water splitting process using solar energy and photovoltaics is a clean way to produce hydrogen, but it suffers from very low efficiency. A promising scheme to produce H 2 from natural gas involves following steps: (i) partial oxidation and reforming of natural gas to syngas, (ii) water-gas shift reaction to convert CO in the syngas to additional H2, (iii) separation of the H2 from CO2, and (iv) CO2 sequestration.; The requirements for the above scheme are (i) a highly active coke resistant catalyst for generation of syngas by direct partial oxidation, (ii) a highly active sulfur tolerant catalyst for the water-gas shift reaction, and (iii) a low cost sorbent with high CO2 adsorption capacity for CO2 sequestration. This dissertation will address the mechanisms of partial oxidation, CO2 adsorption, and water-gas shift catalysis using in situ IR spectroscopy coupled with mass spectrometry (MS). The results from these studies will lead to a better understanding of the reaction mechanism and design of both the catalyst and sorbent for production of hydrogen with zero emissions.; Partial oxidation of methane is studied over Rh/Al2O 3 catalyst to elucidate the reaction mechanism for synthesis gas formation. The product lead-lag relationship observed with in situ IR and MS results revealed that syngas is produced via a two-step reforming mechanism: the first step involving total oxidation of CH4 to CO2 and H 2O and the second step involving the reforming of unconverted methane with CO2 and H2O to form syngas. Furthermore, the Rh on the catalyst surface remains predominantly in the partially oxidized state (Rhdelta+ and Rh0).; For the water-gas shift reaction, addition of Re to the Ni/CeO2 catalyst enhanced the water gas shift activity by a factor of three. The activity of the Ni-Re/CeO2 catalyst was reduced by only 20% in the presence of sulfur compared to a 50% reduction with the Ni/CeO 2 catalyst. These results show that Re not only promotes the water-gas shift reaction but also enhances the sulfur tolerance of the Ni/CeO2 catalyst.; Novel amine based solid sorbents have been developed to capture CO 2 reversibly using temperature-swing adsorption process. The IR study shows that CO2 adsorbs on amine grafted SBA-15 to form carbonates and bicarbonates. Comparison of monoamine and diamine-grafted SBA-15 showed that diamine grafted SBA-15 provides almost twice the active sites for CO 2 adsorption. The adsorption of SO2 on the amine-grafted SBA-15 revealed that SO2 adsorbs irreversibly and the sorbent cannot be regenerated under normal operating conditions.; Results of these studies can be used to enhance the overall conversion of CH4 to H2 thus lowering the cost of H2 product.
机译：氢被认为是下个世纪的燃料。可以通过使用太阳能或核能进行水分解或通过催化裂化和重整化石燃料来生产氢气。使用太阳能和光伏技术的水分解工艺是生产氢气的清洁方法，但是效率极低。一种由天然气生产H 2的有前途的方案包括以下步骤：（i）天然气的部分氧化和重整为合成气；（ii）水煤气变换反应，将合成气中的CO转化为额外的H2；（iii）分离出来自二氧化碳的氢气，以及（iv）隔离二氧化碳；上述方案的要求是（i）通过直接部分氧化生成合成气的高活性耐焦炭催化剂；（ii）用于水煤气变换反应的高活性耐硫催化剂；以及（iii）低成本吸附剂具有高的二氧化碳吸附能力，可以隔离二氧化碳。本文将结合原位红外光谱和质谱（MS），探讨部分氧化，CO2吸附和水煤气变换催化的机理。这些研究的结果将使人们更好地理解反应机理，以及用于生产零排放氢气的催化剂和吸附剂的设计。在Rh / Al2O 3催化剂上研究了甲烷的部分氧化，以阐明合成气形成的反应机理。用原位红外和质谱结果观察到的产物超前-滞后关系表明，合成气是通过两步重整机制生成的：第一步涉及将CH4完全氧化为CO2和H 2O，第二步涉及未转化的甲烷的重整与CO2和H2O形成合成气。此外，催化剂表面上的Rh主要保持部分氧化态（Rhdelta +和Rh0）。对于水煤气变换反应，向Ni / CeO2催化剂中添加Re将水煤气变换活性提高了三倍。在存在硫的情况下，Ni-Re / CeO2催化剂的活性仅降低了20％，而在Ni / CeO 2催化剂中的活性降低了50％。这些结果表明，Re不仅促进了水煤气变换反应，而且还提高了Ni / CeO2催化剂的耐硫性。已经开发出新型的胺基固体吸附剂，以利用变温吸附工艺可逆地捕获CO 2。红外研究表明，CO2吸附在胺接枝的SBA-15上，形成碳酸盐和碳酸氢盐。单胺和二胺接枝的SBA-15的比较表明，二胺接枝的SBA-15提供了几乎两倍的CO 2吸附活性位。 SO 2在胺接枝的SBA-15上的吸附表明，SO 2不可逆地吸附并且在正常操作条件下不能再生吸附剂。这些研究的结果可用于提高CH4到H2的总转化率，从而降低H2产品的成本。

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