Catalytic Hydrotreatment of Kraft Lignin over NiW/SiC: Effective Depolymerization and Catalyst Regeneration

A key challenge in biomass catalytic conversion, especially in pilot and practical scales, is the stability of the catalyst and its support. Depolymerization of Kraft lignin, which is characterized by structural recalcitrance and poison (metal and ash) rich nature, is a good model reaction to demonstrate the above challenge in biomass conversion. In the present study, the potential of SiC-based catalyst (commercially available SiC nanofiber-supported Ni and W, NiW/SiC) in lignin depolymerization was investigated. The results indicate the SiC-based catalyst is a milder catalyst than the state-of-the-art activated carbon-supported catalyst under the identical conditions and supplies a higher liquid product yield. More importantly, the NiW/SiC catalyst can be easily regenerated by coke combustion and subsequent acid washing, which cannot be achieved by either carbon or metallic oxide-supported catalysts. The performance of the regenerated catalyst with only 4% Ni input is almost unchanged compared with that of the fresh catalyst. These results illustrate that SiC combines the advantages of common supports such as activated carbon and metallic oxides and may be generally applicable as catalyst support in biomass conversion

Production of High-Yield Bio-oil with a High Effective Hydrogen/Carbon Molar Ratio through Acidolysis and <i>In Situ</i> Hydrogenation

This paper integrates acidolysis and <i>in situ</i> hydrogenation of biomass to produce bio-oil featuring a high yield and also a high effective hydrogen/carbon molar ratio (H/C_eff). A catalytic amount of trifluoromethanesulfonic acid (HOTf) is found to be very effective to cleave glycosidic bonds in carbohydrates and β-O-4 bonds in lignin, resulting in the formation of various carbohydrate/lignin-derived radicals. The <i>in situ</i> hydrogenation in the presence of Ru/C and H₂ stabilizes the resulting radicals and, thus, prevents their repolymerization. This HOTf–Ru/C system is applicable to a wide range of feedstocks. Typically, the yield of bio-oil (dichloromethane extract) from pine wood at 160 °C can be as high as 43.2 wt % with a H/C_eff of 1.24, which is high enough to be co-processed in the existing refineries

One-Pot Conversion of Carbohydrates in Biomass to Isobutyroin-Rich Branched Oxygenates: Carbohydrate Depolymerization and Methyl Introduction in Supercritical Methanol

This study proposes a one-pot conversion of carbohydrates in biomass to branched oxygenates in methanol, employing noble metal and alkali cation as catalysts. The main product, isobutyroin, is highly concentrated when the reaction temperature and consequent pressure reach the supercritical point of methanol. The type of alkali cation and ratio of feedstock/alkali also significantly influence the production of isobutyroin. In comparison to Na⁺, K⁺ favors the production of isobutyroin from carbohydrates in biomass, especially when a low feedstock/K⁺ ratio is used. The formation of isobutyroin is explained by a series of reactions starting from methanol and cellulose/hemicellulose-derived acetic acid intermediate based on an isotope-labeling experiment. The isobutyroin-rich products can be used as high-quality gasoline precursors or high-value-added chemicals

Localization factors of shopping centers: Case study of shopping centers in Prague

Localisation of economic activities is an often debated issue in the expert literature. In particular, the factors determining the location of retail units in such a complex environment, as is the metropolitan Prague, is a very complicated process. Variance of several meters can determine the entire success or failure of the shopping center. Therefore, the first part of this thesis presents and discuss a broad range of studies and methods with different approaches to determine location analysis. The results of this thesis show the efforts of customers to minimize time and effort spent on shopping, which is just a reflection of the proximity and availability of metro station as the main localization factor in Prague's area. However, not only the location, but also the preferences of customers of specific marketing mix and characteristics affect the success of these centers. Key words: shopping center, localisation factors, Prague, metro, availabilit

SmI₂‑Mediated Intermolecular Coupling of γ‑Lactam <i>N</i>‑α-Radicals with Activated Alkenes: Asymmetric Synthesis of 11-Hydroxylated Analogues of the Lead Compounds CP-734432 and PF-04475270

We report, for the first time, the synthesis of 8-aza-analogues of PGE₂. The SmI₂-mediated cross coupling reactions of γ-lactam-hemiaminal <b>9</b>, lactam 2-pyridyl sulfide <b>17</b>, and lactam 2-pyridyl sulfone <b>18</b> with activated alkenes/alkyne were first developed, giving the corresponding γ-lactams in 49–78%, 45–75%, and 75–90%, respectively. The reactions of lactam 2-pyridyl sulfide and 2-pyridyl sulfone proceeded with ≥12:1 <i>trans</i>-diastereoselectivities. This represents the first intermolecular coupling reaction of the γ-lactam <i>N</i>-α-alkyl radicals of types <b>B</b>, <b>B1</b>, and <b>B2</b> with activated alkenes. Two radical-based mechanisms were suggested. The asymmetric synthesis of the 11-hydroxylated analogue of the highly selective EP₄ receptor agonist PF-04475270 (<b>30</b>), the 11-hydroxylated analogue of ocular hypotensive CP-734432 (<b>31</b>), compounds <b>35</b> and <b>36</b> have been achieved on the basis of this method

The association between -604T>C and stroke in different genetic models.

<p><b>a</b> Dominant model. <b>b</b> Recessive model.</p

SmI₂‑Mediated Intermolecular Coupling of γ‑Lactam <i>N</i>‑α-Radicals with Activated Alkenes: Asymmetric Synthesis of 11-Hydroxylated Analogues of the Lead Compounds CP-734432 and PF-04475270

We report, for the first time, the synthesis of 8-aza-analogues of PGE₂. The SmI₂-mediated cross coupling reactions of γ-lactam-hemiaminal <b>9</b>, lactam 2-pyridyl sulfide <b>17</b>, and lactam 2-pyridyl sulfone <b>18</b> with activated alkenes/alkyne were first developed, giving the corresponding γ-lactams in 49–78%, 45–75%, and 75–90%, respectively. The reactions of lactam 2-pyridyl sulfide and 2-pyridyl sulfone proceeded with ≥12:1 <i>trans</i>-diastereoselectivities. This represents the first intermolecular coupling reaction of the γ-lactam <i>N</i>-α-alkyl radicals of types <b>B</b>, <b>B1</b>, and <b>B2</b> with activated alkenes. Two radical-based mechanisms were suggested. The asymmetric synthesis of the 11-hydroxylated analogue of the highly selective EP₄ receptor agonist PF-04475270 (<b>30</b>), the 11-hydroxylated analogue of ocular hypotensive CP-734432 (<b>31</b>), compounds <b>35</b> and <b>36</b> have been achieved on the basis of this method

Distribution of VEGF receptor-2 genotype and allele among stroke patients and controls in three SNPs.

<p>Distribution of VEGF receptor-2 genotype and allele among stroke patients and controls in three SNPs.</p

The association between +1192C>T and stroke in different genetic models.

<p><b>a</b> Dominant model. <b>b</b> Recessive model.</p

Egger’s linear regression test to measure the funnel plot asymmetric.

<p>Egger’s linear regression test to measure the funnel plot asymmetric.</p