Increment Of Conversion Research Articles

Hydrotreating of Guaiacol and Acetic Acid Blends over Ni2P/ZSM-5 Catalysts: Elucidating Molecular Interactions during Bio-Oil Upgrading.

Catalytic hydrodeoxygenation (HDO) is an effective technology for upgrading pyrolysis bio-oils. Although, in the past years, this process has been extensively studied, the relevance of the cross-reactivity between the numerous chemical components of bio-oil has been scarcely explored. However, molecular coupling can be beneficial for improving the bio-oil characteristics. With the aim of gaining a better understanding of these interactions, this work investigates the catalytic hydrodeoxygenation of mixtures of two typical components of pyrolysis bio-oils: guaiacol and acetic acid. The catalytic tests were carried out employing a bifunctional catalyst based on nickel phosphide (Ni2P) deposited over a commercial nanocrystalline ZSM-5 zeolite. The influence of both hydrogen availability and temperature on the activity and product distribution, was evaluated by carrying out reactions under different H2 pressures (40–10 bar) and temperatures (between 260 and 300 °C). Using blends of both substrates, a partial inhibition of guaiacol HDO occurred because of the competence of acetic acid for the catalytic active sites. Nevertheless, positive interactions were also observed, mainly esterification and acylation reactions, which could enhance the bio-oil stability by reducing acidity, lowering the oxygen content, and increasing the chain length of the components. In this respect, formation of acetophenones, which can be further hydrogenated to yield ethyl phenols, is of particular interest for biorefinery applications. Increasing the temperature results in an increment of conversion but a decrease in the yield of fully deoxygenated molecules due to the production of higher proportion of catechol and related products. Additional experiments performed in the absence of hydrogen revealed that esterification reactions are homogeneously self-catalyzed by acetic acid, while acylation processes are mainly catalyzed by the acidic sites of the zeolitic support.

Reverse atom transfer radical random copolymerization of styrene and methyl methacrylate in the presence of diatomite nanoplatelets

Diatomite nanoplatelets were used for in situ random copolymerization of styrene and methyl methacrylate by reverse atom transfer radical polymerization to synthesize different well‐defined nanocomposites. Inherent features of the pristine diatomite nanoplatelets were evaluated by Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherm, scanning electron microscope, and transmission electron microscope. Gas and size exclusion chromatography was also used to determine conversion and molecular weight determinations, respectively. Considerable increment in conversion (from 81% to 97%) was achieved by adding 3 wt% diatomite nanoplatelets in the copolymer matrix. Moreover, molecular weight of random copolymer chains was increased from 12 890 to 13 960 g·mol−1 by addition of 3 wt% diatomite nanoplatelets; however, polydispersity index (PDI) values increases from 1.36 to 1.59. Proton nuclear magnetic resonance spectroscopy was used to evaluate copolymers composition. Thermal gravimetric analysis results indicate that thermal stability of the nanocomposites is improved by adding diatomite nanoplatelets. Differential scanning calorimetry shows an increase in glass transition temperature from 66°C to 71°C by adding 3 wt% of diatomite nanoplatelets.

Sonochemical synthesis of polymethylmethacrylate to be used as biomaterial

In the present study, the synthesis of PMMA was carried out by emulsion polymerization under ultrasonic radiation, varying the concentration of the anionic surfactant and monomer concentration. Redox process was introduced in order to observe if an increment in conversion was obtained. Characterization was performed by FTIR, DSC, SEM, and 1H-NMR of protons. The synthesis with redox initiation produced PMMA with majorly syndiotatic triads. The synthesis carried out under redox initiation resulted in a large increased in conversion, showing that there is an optimum surfactant/monomer ratio. Scanning Electron Microscopy showed that for low concentrations of surfactant (0.5% p/v) the latex particles presented a rough surface but high surfactant concentration showed nanometric spherical particles with a smooth surface. The study of in vitro biocompatibility by adhesion of osteoblasts on the materials resulted in higher cell adhesion in materials synthesized without redox initiation.

Effect of amines added on Banko coal liquefaction

The effect of the addition of various amines on catalytic and non-catalytic liquefaction of Indonesian Banko coal was studied. For non-catalytic liquefaction a significant increase in coal conversion to THF solubles was observed by the addition of the amines, and the increment in conversion is in the order, secondary aliphatic amine, tertiary aliphatic amine > primary aliphatic amine > aromatic amine. This order is that of the strength of their basicity. For catalytic liquefaction using pyrite the conversion was also increased by the addition of amines, and stronger basic tertiary aliphatic amines gave higher conversion than less basic primary aliphatic amines. The role of amines was considered to induce the higher loading of pyrite on coal surface by the preadsorption of the amine on the surface.

Effect of hydrotreating FCC feedstock on product distribution

The demand of low-sulfur fuels has been increasing during the last 20 years due to environmental concerns about SO x emissions from processing plants and engines. Due to its high contribution to the gasoline pool, hydrotreating fluid catalytic cracking (FCC) feedstock offers several advantages, such as the increase of conversion and yields of gasoline and liquid-phase gas, meanwhile sulfur content in fuels is diminished. However, there are more important factors to be considered when hydrotreating FCC feedstock. In this work, two FCC feedstocks, typical and hydrotreated, were converted in a microactivity test (MAT) reactor, as described by ASTM D-3907-92, at different severities and using two commercial catalysts. Feedstock conversion, product yields and selectivity to valuable products were compared against industrial-scale results predicted by using commercial FCC simulation software. Expected increment in conversion and yield to profitable products was observed when hydrotreated feedstock was used; simulation results follow acceptably MAT results. Some recommendations are given for looking closely at the overall behavior (riser–regenerator), using reliable kinetic models and simulation programs.

Ethylation of benzene with ethanol over substituted large pore aluminophosphate-based molecular sieves

Abstract Ethylation of benzene with ethanol in the vapour phase was studied over AlPO4-5, MAPO-5, ZAPO-5 and MnAPO-5. The products were ethylbenzene (EB), 1,4-diethylbenzene (PDEB), 1,3-diethylbenzene (MDEB) and polyalkyl benzenes (1,2,4- and 1,3,5-triethylbenzene, and 1,2,4,5-tetraethylbenzene). MnAPO-5 was found to be more active than the other catalysts. Maximum conversion (47%) was noted at 400 °C over MnAPO-5. Although isomorphic substitution in MnAPO-5 is nearly the same as in MAPO-5 and ZAPO-5, the increment in conversion was attributed to the presence of unpaired electrons in the d-subshell of manganese. The selectivity of the products was found to decrease with stream but the selectivity to EB showed an increase after 2 h of stream. MnAPO-5 registered nearly 14% yield of EB and 17% yield of DEB, whereas the yield of other products was found to be 16% at maximum conversion.

Preparation of a copolymer of methyl methacrylate with a new monomer, 2,2,6,6‐tetramethyl‐4‐benzyloxyl‐piperidinyl methacrylate, and its initiation of the graft copolymerization of styrene with a controlled radical mechanism

AbstractA copolymer [P(MMA‐co‐TBPM)] was prepared by the radical polymerization of methyl methacrylate (MMA) and 2,2,6,6‐tetramethyl‐4‐benzyloxyl‐piperidinyl methacrylate (TBPM) with azobisisobutyronitrile as an initiator. TBPM was a new monomer containing an activated ester. Both the copolymer and TBPM were characterized with NMR, IR, and gel permeation chromatography in detail. It was confirmed that P(MMA‐co‐TBPM) could initiate the graft polymerization of styrene by the cleavage of the activated ester of the TBPM segment. This process was controllable, and the molecular weight of the graft chain of polystyrene increased with the increment of conversion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4398–4403, 2002

Effects of exogenous hormones and glucose on plasma levels and hepatic metabolism of amino acids in the fetus and in the newborn rat

The present study examines the role of insulin, glucagon and cortisol in the regulation of gluconeogenesis from lactate and amino acids in fetal and newborn rats. Injection of glucagon in the full-term fetal rat caused a rise in glucose (and insulin) and a fall in blood levels of most individual amino acids, stimulated hepatic accumulation of 14C-amino isobutyric acid and 14C-cycloleucine and increased the conversion of 14C lactate, alanine and serine to glucose in vivo and in vitro (liver slices). Such changes were equivalent to the changes seen in 4 h old newborn rats. When glucagon was administered at birth, little difference was observed between control and treated animals in plasma amino acids and a smaller increment in conversion of 14C substrate to glucose occurred. By contrast, insulin injection at birth caused hypoglycemia, suppression of levels of certain amino acids and inhibition of conversion of 14C substrates into glucose. Glucose injection at birth caused elevated glycemia and plasma insulin and suppression of most amino acid levels and of conversion of 14C substrate into glucose. Cortisol injection at birth caused a marked, generalized by hyperaminoacidemia, a stimulation of glucagon secretion and of conversion of 14C substrates into glucose. These observations support the thesis that glucagon plays a major role in the induction of hepatic gluconeogenesis and that insulin acts as an antagonist hormone.