Operando micro-spectroscopy on ZSM-5 containing extrudates during the oligomerization of 1-hexene

The influence of the binder material in an industrial-type catalyst material is often neglected, although the addition of a binder can cause a significant change in the performance of the catalyst. It is difficult to visualize the effects of the different components in these multi-complex materials, and therefore, high spatiotemporal resolution techniques need to be employed. In this work, two complementary micro-spectroscopic techniques; operando UV-vis diffuse reflectance micro-spectroscopy (coupled to on-line mass spectrometry), and in situ confocal fluorescence microscopy were used to investigate the 1-hexene oligomerization reaction. The reaction was performed on both Al2O3- and SiO2-bound ZSM-5-containing extrudates at 250 °C and 300 °C. By employing operando UV-vis micro-spectroscopy, coupled with on-line mass spectrometry, Al2O3-bound catalysts were found to form larger reaction products, as well as more and larger hydrocarbon deposits, compared to the SiO2-bound catalysts. Furthermore, the extrudate containing Al2O3 deactivated slower than the extrudate containing SiO2 binder. Time-resolved chemical maps of the location of the reaction products were visualized using in situ confocal fluorescence microscopy. The maps show that, after reaction, the zeolite crystals contain different coke species than the Al2O3 binder

Chemical Imaging of the Binder-Dependent Coke Formation in Zeolite-Based Catalyst Bodies During the Transalkylation of Aromatics

The choice of binder material, added to a zeolite‐based catalyst body, can significantly influence the catalyst performance during a reaction, i. e. its deactivation and selectivity. In this work the influence of the binder in catalyst extrudates on the formation of hydrocarbon deposits was explored during the transalkylation of toluene with 1,2,4‐trimethylbenzene (1,2,4‐TMB). Using in situ UV‐vis micro‐spectroscopy and ex situ confocal fluorescence microscopy approach, coke species were revealed to predominantly form on the rim of zeolite crystals within Al2O3‐bound extrudates. It was found that this was due to Al migration between the zeolite crystals and the Al2O3‐binder creating additional acid sites near the zeolite external surface. In contrast, minimal isomerization of 1,2,4‐TMB in the SiO2‐bound extrudate allowed greater access to the zeolite internal pore network, creating a more homogeneous coke distribution throughout the zeolite crystals

Chemical Imaging of the Binder-Dependent Coke Formation in Zeolite-Based Catalyst Bodies During the Transalkylation of Aromatics

The choice of binder material, added to a zeolite‐based catalyst body, can significantly influence the catalyst performance during a reaction, i. e. its deactivation and selectivity. In this work the influence of the binder in catalyst extrudates on the formation of hydrocarbon deposits was explored during the transalkylation of toluene with 1,2,4‐trimethylbenzene (1,2,4‐TMB). Using in situ UV‐vis micro‐spectroscopy and ex situ confocal fluorescence microscopy approach, coke species were revealed to predominantly form on the rim of zeolite crystals within Al2O3‐bound extrudates. It was found that this was due to Al migration between the zeolite crystals and the Al2O3‐binder creating additional acid sites near the zeolite external surface. In contrast, minimal isomerization of 1,2,4‐TMB in the SiO2‐bound extrudate allowed greater access to the zeolite internal pore network, creating a more homogeneous coke distribution throughout the zeolite crystals

High‐Pressure Operando UV‐Vis Micro‐Spectroscopy of Coke Formation in Zeolite‐based Catalyst Extrudates during the Transalkylation of Aromatics

The performance of zeolite-based catalyst extrudates can be largely influenced by the choice of binder material. To investigate these binder effects in zeolite-based catalyst extrudates in more detail, high spatiotemporal resolution techniques need to be further developed and employed. In this work, we present a new methodology to investigate binder effects in catalyst extrudates at different reaction pressures using operando UV-vis diffuse reflectance (DR) micro-spectroscopy coupled with on-line gas chromatography. We have studied mm-sized zeolite H-ZSM-5-containing extrudates with either Al2O3 or SiO2 binder material, during the transalkylation of toluene with 1,2,4-trimethylbenzene at 450 °C and at a pressure of either 1 or 5 bar. Using this technique, it was revealed that the binder material significantly influenced catalyst deactivation at different reaction pressures. By subsequent mapping of the cross sections of the cylindrical catalyst extrudates using UV-vis micro-spectroscopy, it was shown that the SiO2-bound extrudate formed poly-aromatic coke molecules homogeneously throughout the entire extrudate, whereas for the Al2O3-bound extrudate a coke ring formed that moved inwards with increasing reaction time. Notably, the developed methodology is not limited to the transalkylation reaction, and can also be used to gain more insight into binder effects during a variety of important catalytic reactions

High-Pressure Operando UV-Vis Micro-Spectroscopy of Coke Formation in Zeolite-based Catalyst Extrudates during the Transalkylation of Aromatics

The performance of zeolite-based catalyst extrudates can be largely influenced by the choice of binder material. To investigate these binder effects in zeolite-based catalyst extrudates in more detail, high spatiotemporal resolution techniques need to be further developed and employed. In this work, we present a new methodology to investigate binder effects in catalyst extrudates at different reaction pressures using operando UV-vis diffuse reflectance (DR) micro-spectroscopy coupled with on-line gas chromatography. We have studied mm-sized zeolite H-ZSM-5-containing extrudates with either Al2O3 or SiO2 binder material, during the transalkylation of toluene with 1,2,4-trimethylbenzene at 450 °C and at a pressure of either 1 or 5 bar. Using this technique, it was revealed that the binder material significantly influenced catalyst deactivation at different reaction pressures. By subsequent mapping of the cross sections of the cylindrical catalyst extrudates using UV-vis micro-spectroscopy, it was shown that the SiO2-bound extrudate formed poly-aromatic coke molecules homogeneously throughout the entire extrudate, whereas for the Al2O3-bound extrudate a coke ring formed that moved inwards with increasing reaction time. Notably, the developed methodology is not limited to the transalkylation reaction, and can also be used to gain more insight into binder effects during a variety of important catalytic reactions

Chemical Imaging of the Binder‐Dependent Coke Formation in Zeolite‐Based Catalyst Bodies During the Transalkylation of Aromatics

The choice of binder material, added to a zeolite‐based catalyst body, can significantly influence the catalyst performance during a reaction, i. e. its deactivation and selectivity. In this work the influence of the binder in catalyst extrudates on the formation of hydrocarbon deposits was explored during the transalkylation of toluene with 1,2,4‐trimethylbenzene (1,2,4‐TMB). Using in situ UV‐vis micro‐spectroscopy and ex situ confocal fluorescence microscopy approach, coke species were revealed to predominantly form on the rim of zeolite crystals within Al2O3‐bound extrudates. It was found that this was due to Al migration between the zeolite crystals and the Al2O3‐binder creating additional acid sites near the zeolite external surface. In contrast, minimal isomerization of 1,2,4‐TMB in the SiO2‐bound extrudate allowed greater access to the zeolite internal pore network, creating a more homogeneous coke distribution throughout the zeolite crystals

High-Pressure Operando UV-Vis Micro-Spectroscopy of Coke Formation in Zeolite-based Catalyst Extrudates during the Transalkylation of Aromatics

The performance of zeolite-based catalyst extrudates can be largely influenced by the choice of binder material. To investigate these binder effects in zeolite-based catalyst extrudates in more detail, high spatiotemporal resolution techniques need to be further developed and employed. In this work, we present a new methodology to investigate binder effects in catalyst extrudates at different reaction pressures using operando UV-vis diffuse reflectance (DR) micro-spectroscopy coupled with on-line gas chromatography. We have studied mm-sized zeolite H-ZSM-5-containing extrudates with either Al2O3 or SiO2 binder material, during the transalkylation of toluene with 1,2,4-trimethylbenzene at 450 °C and at a pressure of either 1 or 5 bar. Using this technique, it was revealed that the binder material significantly influenced catalyst deactivation at different reaction pressures. By subsequent mapping of the cross sections of the cylindrical catalyst extrudates using UV-vis micro-spectroscopy, it was shown that the SiO2-bound extrudate formed poly-aromatic coke molecules homogeneously throughout the entire extrudate, whereas for the Al2O3-bound extrudate a coke ring formed that moved inwards with increasing reaction time. Notably, the developed methodology is not limited to the transalkylation reaction, and can also be used to gain more insight into binder effects during a variety of important catalytic reactions

Swelling Enhanced Remanent Magnetization of Hydrogels Cross-Linked with Magnetic Nanoparticles

Hydrogels that are pH-sensitive and partially cross-linked by cobalt ferrite nanoparticles exhibit remarkable remanent magnetization behavior. The magnetic fields measured outside our thin disks of ferrogel are weak, but in the steady state, the field dependence on the magnetic content of the gels and the measurement geometry is as expected from theory. In contrast, the time-dependent behavior is surprisingly complicated. During swelling, the remanent field first rapidly increases and then slowly decreases. We ascribe the swelling-induced field enhancement to a change in the average orientation of magnetic dipolar structures, while the subsequent field drop is due to the decreasing concentration of nanoparticles. During shrinking, the field exhibits a much weaker time dependence that does not mirror the values found during swelling. These observations provide original new evidence for the markedly different spatial profiles of the pH during swelling and shrinking of hydrogels