Mono-, Bi-, and Tri-Metallic DES Are Prepared from Nb, Zr, and Mo for n-Butane Selective Oxidation via VPO Catalyst

In recent work, deep eutectic solvents (DESs) as ionic liquid analogues have been abundantly used in catalysis. Herein, vanadium phosphorus oxide (VPO) catalysts were synthesized from mono-, bi-, and tri- metallic DES of Nb, Zr, and Mo metal dopants as structure-directing agents and electronic promoters for n-butane selective oxidation towards maleic anhydride. Higher MA selectivity and larger n-butane conversion was successfully obtained using the newly developed catalysts, while oxidation by-product COx (CO, CO2) was minimized. Characterization techniques including FTIR, DSC, XRD, TEM, SEM, EDS, Raman spectroscopy, TGA, XPS, and NH3-TPD were employed to fully characterize the DESs, precursors and catalysts. This work led to an increase of 7.8% in MA mass yield with 16% more n-butane conversion as compared to an unpromoted VPO catalyst. Moreover, the utilization of a low-carbon alkane brought in a green impact on the chemical plant as well as the environment.

Co-Aromatization of n-Butane and Methanol over PtSnK-Mo/ZSM-5 Zeolite Catalysts: The Promotion Effect of Ball-Milling

The ball-milling (BM) method benefits the stabilization and dispersion of metallic particles for the preparation of the PtSnK–Mo/ZSM-5 catalyst. Based on the TPR, H2-TPD, XPS, and CO-FTIR results, the Pt–SnOx and MoOx species were formed separately on the BM sample. During the aromatization of cofeeding the n-butane with methanol, the yield of the aromatics is 59 wt.% at a n-butane conversion of 86% at 475 °C over the Pt Mo BM catalyst. The more weak acid sites also contribute to the aromatics formation with the less light alkanes formation. For the Pt Ga catalysts, the slow loss of activity suggests that the BM method can restrain the coke deposition on the Pt-SnOx species, because of a certain distance between the Pt–SnOx and GaOx species on the surface of ZSM-5.

Preparation of Au Supported ZSM-5 Catalysts and its Special Performance in the Catalytic Cracking of Butane Reaction

Au/ZSM-5 was prepared by improved desorption-precipitation (DP) method using urea as precipitant. Au-samples were characterized by TEM, UV-Vis, XRD, pyridine-FTIR, FTIR and the other techniques. The catalytic performance of Au/ZSM-5 catalysts was carried out on the catalytic cracking of butane by mini-scale pulse reactor. Results showed that: 2.0wt% loading Au/ZSM-5 catalyst obtained the best activity that the n-butane conversion rate comes to 58% by weight,60% olefin selectivity and 10% aromatics selectivity; the i-butane conversion rate comes to 53%, 35% olefin selectivity and 15% aromatics selectivity.

Transient Redox Activity of Vanadyl Pyrophosphate at Ambient and Elevated Pressure

The transient catalytic activity of vanadyl pyrophosphate (VPP) catalyst was studied at ambient and elevated pressure (4.1 bar) and a wide range of operating conditions. The range included the commercial operating conditions typical of fixed bed, fluidized bed and circulating fluidized beds (CFB) for the partial oxidation of n-butane to maleic anhydride (MA). The maleic anhydride yield improved by increasing the feed oxygen molar fraction, temperature and pressure. When the catalyst was cycled between an oxidizing (synthetic air) and a reducing environment; yield increased with an increase in the catalyst residence time in the oxidizing environment. This effect was more pronounced at higher pressure. At ambient pressure, MA selectivity varied between 50-73 % while it decreased to about 48-54 % at a pressure of 4.1 bar. A strong MA selectivity dependency on feed composition was observed when the oxidation time was in the range of actual industrial reactors (< 1 minute). Selectivity data suggested that different oxygen species might be responsible for CO formation compared to other products such as CO2 and MA. Under oxidizing feed conditions (oxygen/n-butane ≥ than 3.7), an increase in n butane conversion was the main contributor to improved MA yield: n-butane conversion increased by about 70 % when the catalyst oxidation time extended from 0.3 to 10 minute. While, under fuel rich feed conditions, typical of industrial CFB operations, both MA selectivity and n-butane conversion contributed to enhancement in MA yield. Depending on the feed composition, MA selectivity increases by about 16-30 % and n butane conversion increases by about 32-55 % by extending the catalyst oxidation time. These results show the critical importance of catalyst oxidation time on reaction yield improvement especially when operating under fuel rich feed conditions. The surface adsorbed or surface lattice oxygen species were suggested to be the main responsible for n butane activation. While, the contribution of catalyst’s sub-surface lattice oxygen was believed to be very limited at fuel rich feed conditions. Under these conditions, catalyst over-reduction cannot be effectively compensated even after excessive catalyst regeneration and presence of gas phase oxygen is critical to maintain a high catalytic activity. As the reactor pressure increased to 4.1 bar, up to 60 % increase in n butane conversion accompanied by 100 % increase in oxygen conversion was observed. MA selectivity decreased by about 20 % on average but the increase in n-butane conversion resulted in an overall yield improvement of up to 30 %. Data show that the catalytic performance could be enhanced at certain combination of reactor pressure and temperature.

Performance Analysis of Butane Direct Internal Reforming SOFC at Intermediate Temperature

In this work, the performance of solid oxide fuel cells at an intermediate temperature (600°C) that uses reformate gas and butane as fuel sources is investigated. Anode materials consisting of Ni and Ce0.9Gd0.1O2 (CGO91) and Ni and Y0.08Zr0.92O2 (8YSZ) are tested as steam reforming catalysts. Anode materials using NiO/CGO91 steam to carbon ratio of 3 and butane as the fuel source result in the better performance. However, even if the gas hourly space velocity is very low and NiO/CGO91 is used as the anode, the conversion of butane is not 100%. Additives are added to the NiO/CGO91 materials to increase the conversion of butane. Among the additives tested, the Rh is the most effective, resulting in 100% of butane conversion and no carbon deposition. Moreover, Rh added NiO/CGO91 SOFC single cell have a very low degradation rate when butane is directly used in conditions of steam to carbon ratio 3.