The Influence of Active Phase Loading on the Hydrodeoxygenation (HDO) of Ethylene Glycol over Promoted MoS2_{2}/MgAl2_{2}O4_{4} Catalysts

The hydrodeoxygenation (HDO) of ethylene glycol over MgAl$_{2}$O$_{4}$ supported NiMo and CoMo catalysts with around 0.8 and 3 wt% Mo loading was studied in a continuous flow reactor setup operated at 27 bar H$_{2}$ and 400 °C. A co-feed of H2S of typically 550 ppm was beneficial for both deoxygenation and hydrogenation and for enhancing catalyst stability. With 2.8-3.3 wt% Mo, a total carbon based gas yield of 80-100 % was obtained with an ethane yield of 36-50 % at up to 118 h on stream. No ethylene was detected. A moderate selectivity towards HDO was obtained, but cracking and HDO were generally catalyzed to the same extent by the active phase. Thus, the C2/C1 ratio of gaseous products was 1.1-1.5 for all prepared catalysts independent on Mo loading (0.8-3.3 wt%), but higher yields of C1-C3 gas products were obtained with higher loading catalysts. Similar activities were obtained from Ni and Co promoted catalysts. For the low loading catalysts (0.83-0.88 wt% Mo), a slightly higher hydrogenation activity was observed over NiMo compared to CoMo, giving a relatively higher yield of ethane compared to ethylene. Addition of 30 wt% water to the ethylene glycol feed did not result in significant deactivation. Instead, the main source of deactivation was carbon deposition, which was favored at limited hydrogenation activity and thus, was more severe for the low loading catalysts

Operando XAS/XRD and Raman Spectroscopic Study of Structural Changes of the Iron Molybdate Catalyst during Selective Oxidation of Methanol

The structural changes of an iron molybdate/molybdenum oxide (Mo/Fe=2.0) catalyst for the selective oxidation of methanol to formaldehyde were studied using combined operando X‐ray absorption spectroscopy (XAS) and X‐ray diffraction (XRD) as well as operando Raman spectroscopy. Under operating conditions, the Mo K‐edge XANES spectra showed a transition from a mixture of α‐MoO$_{3}$ and Fe$_{2}$(MoO$_{4}$)$_{3}$ towards only Fe$_{2}$(MoO$_{4}$)$_{3}$. XRD and Raman spectroscopy also showed disappearance of the α‐MoO3 phase with time on stream. The results evidenced that the α‐MoO3 component evaporated completely, while the Fe$_{2}$(MoO$_{4}$)$_{3}$ component remained stable. This was linked to a decrease in catalytic activity. Further studies unraveled that the rate of α‐MoO$_{3}$ evaporation increased with increasing MeOH concentration, decreasing O$_{2}$ concentration and increasing temperature. The simultaneous measurements of catalytic activity and spectroscopy allowed to derive a structure‐activity relationship showing that α‐MoO$_{3}$ evaporation needs to be prevented to optimize MoO$_{3}$‐based catalysts for selective oxidation of methanol

Hydrodeoxygenation (HDO) of aliphatic oxygenates and phenol over NiMo/MgAl2_{2}O4_{4}: Reactivity, inhibition, and catalyst reactivation

This study provides new insights into sustainable fuel production by upgrading bio-derived oxygenates by catalytic hydrodeoxygenation (HDO). HDO of ethylene glycol (EG), cyclohexanol (Cyc), acetic acid (AcOH), and phenol (Phe) was investigated using a Ni-MoS$_{2}$/MgAl$_{2}$O$_{4}$ catalyst. In addition, HDO of a mixture of Phe/EG and Cyc/EG was studied as a first step towards the complex mixture in biomass pyrolysis vapor and bio-oil. Activity tests were performed in a fixed bed reactor at 380–450 °C, 27 bar H2, 550 vol ppm H2S, and up to 220 h on stream. Acetic acid plugged the reactor inlet by carbon deposition within 2 h on stream, underlining the challenges of upgrading highly reactive oxygenates. For ethylene glycol and cyclohexanol, steady state conversion was obtained in the temperature range of 380–415 °C. The HDO macro-kinetics were assessed in terms of consecutive dehydration and hydrogenation reactions. The results indicate that HDO of ethylene glycol and cyclohexanol involve different active sites. There was no significant influence from phenol or cyclohexanol on the rate of ethylene glycol HDO. However, a pronounced inhibiting effect from ethylene glycol on the HDO of cyclohexanol was observed. Catalyst deactivation by carbon deposition could be mitigated by oxidation and re-sulfidation. The results presented here demonstrate the need to address differences in oxygenate reactivity when upgrading vapors or oils derived from pyrolysis of biomass

Assessment of xenoestrogenic exposure by a biomarker approach: application of the E-Screen bioassay to determine estrogenic response of serum extracts

BACKGROUND: Epidemiological documentation of endocrine disruption is complicated by imprecise exposure assessment, especially when exposures are mixed. Even if the estrogenic activity of all compounds were known, the combined effect of possible additive and/or inhibiting interaction of xenoestrogens in a biological sample may be difficult to predict from chemical analysis of single compounds alone. Thus, analysis of mixtures allows evaluation of combined effects of chemicals each present at low concentrations. METHODS: We have developed an optimized in vitro E-Screen test to assess the combined functional estrogenic response of human serum. The xenoestrogens in serum were separated from endogenous steroids and pharmaceuticals by solid-phase extraction followed by fractionation by high-performance liquid chromatography. After dissolution of the isolated fraction in ethanol-DMSO, the reconstituted extract was added with estrogen-depleted fetal calf serum to MCF-7 cells, the growth of which is stimulated by estrogen. After a 6-day incubation on a microwell plate, cell proliferation was assessed and compared with the effect of a 17-beta-estradiol standard. RESULTS AND CONCLUSIONS: To determine the applicability of this approach, we assessed the estrogenicity of serum samples from 30 pregnant and 60 non-pregnant Danish women thought to be exposed only to low levels of endocrine disruptors. We also studied 211 serum samples from pregnant Faroese women, whose marine diet included whale blubber that contain a high concentration of persistent halogenated pollutants. The estrogenicity of the serum from Danish controls exceeded the background in 22.7 % of the cases, while the same was true for 68.1 % of the Faroese samples. The increased estrogenicity response did not correlate with the lipid-based concentrations of individual suspected endocrine disruptors in the Faroese samples. When added along with the estradiol standard, an indication of an enhanced estrogenic response was found in most cases. Thus, the in vitro estrogenicity response offers a promising and feasible approach for an aggregated exposure assessment for xenoestrogens in serum

A methodology for the evaluation of competition policy

The paper develops a methodology for the evaluation of competition policy. Based on the existing literature and experiences with policy evaluations in other areas of economic activity, the three-step / nine-building-blocks methodology provides guidance for evaluation projects and also assists in the identification of avenues for further academic research