In this work, we investigated the application of ion transport membranes (ITM) in the co-production of hydrogen (H 2 ) and ethylene (C 2 H 4 ) through water (H 2 O) splitting and ethane (C 2 H 6 ) oxidative dehydrogenation, respectively, using BaFe 0.9 Zr 0.1 O 3-δ (BFZ) mixed ionic-electronic conducting (MIEC) materials. Experimental measurements showed that a 1.1mm thick BFZ membrane exhibited an oxygen flux (J O2 ) of ≈ 2.0 µmole/cm 2 /sec when operating at T=900°C with inlet steam mole fraction at the feed side equal to X H2O =50% and inlet ethane mole fraction at the fuel side equal to X C2H6 =10%. Under the same conditions, ethane conversion and selectivity to ethylene were 95% and 83%, respectively. Lowering the temperature to T=850°C decreased J O2 to ≈ 1.0 µmole/cm 2 /sec and conversion of ethane to 79%, but the selectivity to ethylene increased to 93%. The proposed technology shows significant performance advantages compared to traditional ethane cracking and hence is a promising method for chemical conversion processes.
Recent major discoveries of gas and oil in the United States in shale plays have significantly increased the amount of ethane available for steam-cracking to produce ethylene; and numerous large petrochemical companies have built new ethane crackers on the U.S. Gulf Coast since 2016. Steam-cracking, however, is energy intensive; and there is a need to develop moreenergy-efficient processes to produce ethylene. Oxidative dehydrogenation of ethane to ethylene in an oxygen-ion-transportmembrane reactor is thought to be one such process; and experimental work has demonstrated that (1) a mixed ionic and electronic conducting membrane with the stoichiometry BaFe 0.9 Zr 0.1 O 3−δ is capable of splitting steam into gaseous hydrogen and oxygen ions on the feed gas−membrane interface, and (2) the oxygen ions can diffuse through the membrane to react with ethane on the fuel-side gas−membrane interface, producing ethylene in yields ranging from 46 to 77% at ethylene selectivities as high as 98%.
The use of metal−organic frameworks (MOFs) as precursors for the manufacture of heterogeneous catalysts has gained a great deal of attention over the last decade. By subjecting a given MOF to pyrolysis, electrochemical degradation, or other treatments under a controlled atmosphere, (supported) metal (oxide) nanoparticles with very narrow size distributions can be obtained, opening the door to the design of more efficient catalytic solids. Here, we demonstrate the benefits of steam during the controlled decomposition of two different MOF structures (Basolite F300(Fe) and In@ZIF-67(Co)) and the consequences of treatment under this mildly oxidizing atmosphere on the properties of the resulting catalysts for the direct hydrogenation of CO 2 to hydrocarbons and methanol. In-depth characterization demonstrates that steam addition helps to control the phase composition both before and after catalysis; additionally, it results in the formation of smaller nanoparticles, thus leading to more efficient catalysts in comparison with conventional pyrolysis.
Since its discovery in 1982, oxidative coupling of methane (OCM) has been considered one of the most promising approaches for the on-purpose synthesis of ethylene.The development of more selective catalysts is essential to improve process economics. In this work, undoped neodymium oxide as well as neodymium oxide doped with high (20%) and low (2.5%) levels of strontium were tested in a high-throughput fashion covering a wide range of operating conditions. The catalysts were shown to be able to achieve greater than 18% C 2 + yield. Space velocity was shown to play a significant role in C 2 + selectivity. For a methane to oxygen feed ratio of 3.5, selectivity increased with increasing space velocity, reaching a maximum of 62% at a methane conversion of 30% at an optimal space velocity of $250,000 ml/h/g. The difference in activity between the three samples was linked to the contribution of different oxygen centers.
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