Modeling the selective oxidation of n-butane to maleic anhydride: From active site to industrial reactor

Room temperature catalytic upgrading of unpurified lignin depolymerization oil into bisphenols and butene-2

Lignin is the largest source of renewable aromatics on earth. Despite numerous techniques for lignin depolymerization into mixtures of valuable monomers, methods for their upgrading into final products are scarce. The state of the art upgrading methods generally rely on catalytic funneling, requiring high temperatures, catalyst loadings and hydrogen pressure, and lead to the loss of functionality and bio-based carbon content. Here an alternative approach is presented, whereby the target monomers are selectively converted in unpurified mixtures into easily separable final products under mild conditions. We use reductive catalytic fractionation of wood to convert lignin into iso-eugenol and propenyl syringol enriched oil followed by an olefin metathesis to yield bisphenols and butene-2, thus, valorizing all bio-based carbons. To further demonstrate the synthetic utility of the obtained bisphenols we converted them into polyesters with a high glass transition temperature (Tg = 140.3 °C) and thermal stability (Td50% = 330 °C).

Efficient separation of butane isomers via ZIF-8 slurry on laboratory- and pilot-scale

n-butane and isobutane are important petrochemical raw materials. Their separation is challenging because of their similar properties, including boiling point. Here, we report a zeolitic imidazolate framework-8 (ZIF-8)/N,N-Dimethylpropyleneurea (DMPU)-water slurry as sorption material to separate butane mixtures. The isobutane/n-butane selectivity of ZIF-8/DMPU-water slurries is as high as 890 with high kinetic performance, which transcends the upper limit of various separation materials or membranes reported in the literature. More encouragingly, a continuous pilot separation device was established, and the test results show that the purity and recovery ratio of isobutane product are 99.46 mol% and 87%, respectively, which are superior to the corresponding performance (98.56 mol% and 54%) of the industrial distillation tower. To the best of our knowledge, the use of metal-organic frameworks (MOFs) for gas separation in pilot scale remains underexplored, and thus this work provides a step forward to the commercial application of MOFs in gas separation.

The separation of butane isomers, raw materials in petrochemical industry, is challenging. Here the authors report the separation of n-butane and isobutane using a metal-organic framework slurry; the separation can be performed at large scale in a pilot-scale separation tower.

Reaction Behaviors and Crystal Transformation of Industrial Vanadium-Phosphorus-Oxygen (VPO) Catalysts for n-Butane Oxidation

A long-time evaluation of n-butane oxidation over an industrial vanadium-phosphorus-oxygen (VPO) catalyst was implemented. The catalytic performances for n-butane oxidation during this period were obtained. It was shown that the conversion of n-butane increased with the evaluation time, but the selectivity of the maleic anhydride (MA) product decreased gradually. To investigate the crystal transformation of the VPO catalyst, the properties of fresh and evaluated VPO catalysts were measured by a series of characterization methods, including X-ray diffraction (XRD), N₂ adsorption and desorption, NH₃-temperature programmed desorption (TPD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that the acidities and valence of vanadium increased after evaluation due to the appearance of a β-VOPO₄ phase. The crystal transformation would increase the activity for n-butane oxidation. Meanwhile, during the evaluation period, the decrease in selectivity of the MA product should be related to the decreasing percentage of Lat-O species in the VPO catalyst.