Conversion of Lignin to Chemical Intermediates:a Study of Pyrolysis of Kraft Lignin

Experiments of pyrolysis of commercial Kraft lignin have been realized in the 250-550 °C range. Product analyses have been performed by FTIR, GC-MS, EDX analyses. The main goal of the work is to optimize the experiments in terms of liquid yield, reduction of oxygen content in the resulting biochar, and removal of sulfur, found mainly in the gas phase. It has been concluded that the amount of the starting lignin charged in the reactor must be limited to be fully positioned in the heating chamber also during high temperature treatment. Sulfur may be partially removed in the gas phase as H2S and CH3SH mainly, by a pre-treatment at 250 °C. The maximum amount of liquid product, mainly constituted by methoxy- and alkyl-methoxy-phenols, and the maximum solid deoxygenation are both obtained at 550 °C

On the Role of Support in Metallic Heterogeneous Catalysis: A Study of Unsupported Nickel\u2013Cobalt Alloy Nanoparticles in Ethanol Steam Reforming

(Co, Ni) bimetallic nanoparticles have been prepared by reducing Ni and Co chloride solutions with sodium borohydride. The obtained materials have been characterized as cast and/or after annealing by means of XRD, magnetic measurements, IR spectroscopy, FE-SEM and TEM microscopies. The resulting nanomaterials, originally amorphous, crystallize into the cubic structure cF4-Cu as homogeneous (Co, Ni) solid solution alloy and with the additional presence of Boron containing phases due to the residual preparation impurities. The bimetallic nanoparticles are active in ethanol conversion in the presence of steam. For low Boron catalysts, the addition of Nickel to Cobalt nanoparticles improves the catalytic activity in ethanol steam reforming allowing yields as high as 87% at 773 K, at high space velocities (GHSV 324,000 h 121 ). The performances of the catalytic unsupported nanoparticles with a Ni/Co atomic ratio equal to 0.26 appear to be better than those of conventional supported catalysts. The state of Boron impurities affect catalytic activity of bimetallic (Co, Ni) NPs. Carbonaceous materials, such as carbon nanotubes and graphitic carbon, form on the catalyst surface upon reaction. Graphical Abstract: [Figure not available: see fulltext.]

Ethanol and diethyl ether catalytic conversion over commercial alumina and lanthanum-doped alumina: Reaction paths, catalyst structure and coking

Commercial high-pore-volume alumina and La-doped aluminas have been characterized and tested as catalysts for ethanol conversion to ethylene and diethyl ether and for diethyl ether cracking. In order to go deeper on reaction paths and mechanisms, steady state, TPSR and static experiments in an IR cell were performed. It is established that ethylene forms from ethanol by two parallel ways: i) cracking of ethoxy groups that occurs already at low temperature, and ii) the parallel synthesis and cracking of DEE at intermediate temperatures. Coordination of diethyl ether on Lewis sites represents the first step in its decomposition path. Lewis bonded DEE first cracks to ethoxy species and ethylene gas, while ethoxy species in part crack to a second step to another ethylene gas molecule and in part (only at low temperature) can desorb as gaseous ethanol. Commercial low loading lanthanum-doped alumina contain dispersed La3+-O2 12species mainly interacting with the most reactive defect, edge and corner sites of alumina nanocrystals. At higher loading (4 wt% La2O3) very small LaxOyclusters also appear. Lanthanum doping slightly reduces the number of active sites for ethanol dehydration as well as for DEE cracking, thus reducing catalytic activity, but does not modify significantly selectivities and ethylene yields at high temperature. However, it also considerably reduces the amount of carbonaceous residues formed upon both reactions over the catalyst. Thus, La-doping is proposed as a way to improve the alumina catalyst stability in the process. Catalytic cracking of DEE at 673 K does not represent a good way to remove odorous and dense DEE vapours from air, due to the coproduction of small amounts of acetaldehyde together with ethylene

A study of Ni/La-Al 2 O 3 catalysts: A competitive system for CO 2 methanation

Ni/La-\u3b3-Al 2 O 3 samples containing 13.6 wt.% Ni and a variable amount of lanthana (0, 4, 14 and 37 wt.%) were prepared by incipient wetness impregnation, using silica-free \u3b3-Al 2 O 3 support. The materials were characterized, as such or after reaction, with XRD, H 2 -TPR, IR, UV\u2013vis-NIR, XPS and FE-SEM techniques. They were tested as catalysts for CO 2 methanation at atmospheric pressure at GHSV 55000 h 121 . The reaction is under kinetic control at T < 650\u2013673 K, while the product mixture is under thermodynamic control above this temperature range. Lanthanum addition strongly increases the activity of Ni/\u3b3-Al 2 O 3 for CO 2 methanation. Methane selectivity is increased to nearly 100% at low temperatures (T < 650 K). The CO 2 methanation reaction on La-doped Ni/\u3b3-Al 2 O 3 occurs with similar activation energies (80 kJ/mol), and with slightly higher reaction order for hydrogen and lower reaction order for CO 2 than those observed for undoped Ni/\u3b3-Al 2 O 3 . Lanthanum acts as a promoter because of the stronger basicity of the lanthana-alumina support allowing stronger adsorption of CO 2 as surface carbonates that can be act as \u201creactant reservoirs\u201d. The Ni/La-alumina catalysts studied here are similarly effective as Ru/alumina catalysts for the selective CO 2 methanation at low temperature and atmospheric pressure

Gastro-intestinal emergency surgery: Evaluation of morbidity and mortality. Protocol of a prospective, multicenter study in Italy for evaluating the burden of abdominal emergency surgery in different age groups. (The GESEMM study)

Gastrointestinal emergencies (GE) are frequently encountered in emergency department (ED), and patients can present with wide-ranging symptoms. more than 3 million patients admitted to US hospitals each year for EGS diagnoses, more than the sum of all new cancer diagnoses. In addition to the complexity of the urgent surgical patient (often suffering from multiple co-morbidities), there is the unpredictability and the severity of the event. In the light of this, these patients need a rapid decision-making process that allows a correct diagnosis and an adequate and timely treatment. The primary endpoint of this Italian nationwide study is to analyze the clinicopathological findings, management strategies and short-term outcomes of gastrointestinal emergency procedures performed in patients over 18. Secondary endpoints will be to evaluate to analyze the prognostic role of existing risk-scores to define the most suitable scoring system for gastro-intestinal surgical emergency. The primary outcomes are 30-day overall postoperative morbidity and mortality rates. Secondary outcomes are 30-day postoperative morbidity and mortality rates, stratified for each procedure or cause of intervention, length of hospital stay, admission and length of stay in ICU, and place of discharge (home or rehabilitation or care facility). In conclusion, to improve the level of care that should be reserved for these patients, we aim to analyze the clinicopathological findings, management strategies and short-term outcomes of gastrointestinal emergency procedures performed in patients over 18, to analyze the prognostic role of existing risk-scores and to define new tools suitable for EGS. This process could ameliorate outcomes and avoid futile treatments. These results may potentially influence the survival of many high-risk EGS procedure

High–temporal resolution profiling reveals distinct immune trajectories following the first and second doses of COVID-19 mRNA vaccines

Knowledge of the mechanisms underpinning the development of protective immunity conferred by mRNA vaccines is fragmentary. Here, we investigated responses to coronavirus disease 2019 (COVID-19) mRNA vaccination via high–temporal resolution blood transcriptome profiling. The first vaccine dose elicited modest interferon and adaptive immune responses, which peaked on days 2 and 5, respectively. The second vaccine dose, in contrast, elicited sharp day 1 interferon, inflammation, and erythroid cell responses, followed by a day 5 plasmablast response. Both post-first and post-second dose interferon signatures were associated with the subsequent development of antibody responses. Yet, we observed distinct interferon response patterns after each of the doses that may reflect quantitative or qualitative differences in interferon induction. Distinct interferon response phenotypes were also observed in patients with COVID-19 and were associated with severity and differences in duration of intensive care. Together, this study also highlights the benefits of adopting high-frequency sampling protocols in profiling vaccine-elicited immune responses

A Study on CO2 Methanation and Steam Methane Reforming over Commercial Ni/Calcium Aluminate Catalysts

Three Ni-based natural gas steam reforming catalysts, i.e., commercial JM25-4Q and JM57-4Q, and a laboratory-made catalyst (26% Ni on a 5% SiO2–95% Al2O3), are tested in a laboratory reactor, under carbon dioxide methanation and methane steam reforming operating conditions. The laboratory catalyst is more active in both CO2 methanation (equilibrium is reached at 623 K with 100% selectivity) and methane steam reforming (92% hydrogen yield at 890 K) than the two commercial catalysts, likely due to its higher nickel loading. In any case, commercial steam reforming catalysts also show interesting activity in CO2 methanation, reduced by K-doping. The interpretation of the experimental results is supported by a one-dimensional (1D) pseudo-homogeneous packed-bed reactor model, embedding the Xu and Froment local kinetics, with appropriate kinetic parameters for each catalyst. In particular, the H2O adsorption coefficient adopted for the commercial catalysts is about two orders of magnitude higher than for the laboratory-made catalyst, and this is in line with the expectations, considering that the commercial catalysts have Ca and K added, which may promote water adsorption

Methanation of carbon dioxide on Ru/Al2O3 and Ni/Al2O3 catalysts at atmospheric pressure: Catalysts activation, behaviour and stability

The methanation of carbon dioxide has been studied over 3% Ru/Al2O3 and 20% Ni/Al2O3 commercial catalysts. Experiments have been performed in diluted conditions in a flow catalytic reactor with a continuous IR detection of products. The data, reported here, confirm that 3% Ru/Al2O3 is an excellent catalyst for CO2 methanation (96% methane yield with no CO coproduction at 573 K at 15,000 h-1 GHSV in excess hydrogen). The performance is better than that of Ni/Al2O3 catalyst. The reaction orders over both catalysts with respect to both hydrogen and CO2 were determined over conditioned catalysts. A conditioning of the Ru/Al2O3 catalyst by reactant gas stream was found to be needed and more effective than conditioning in hydrogen, possibly because water vapour formed during methanation reaction will react to remove chlorine impurities from catalyst surface Conditioned Ru/Al2O3 catalyst was found to retain stable high activity after different shut-down and start-up procedures, thus being possibly applicable in intermittent conditions

On the use of infrared spectrometer as detector for Temperature Programmed (TP) techniques in catalysts characterization

IR spectrometer has been successfully applied as detector for temperature-programmed techniques, i.e. NH3-TPD and H2-TPR, demonstrating an excellent flexibility, robustness and effectiveness in the proposed study. IR allowed also to detect unexpected or coproduced compounds and to avoid in many cases the expensive coupling of different techniques. For NH3-TPD, a successful qualitative and quantitative determination has been achieved with an excellent signal/noise ratio and on materials characterized by different: Br\uf8nsted/Lewis acidity, thermal pretreatment, doping elements and oxidation activity. For H2-TPR, the reducibility of different supported Ni-based catalytic systems has been successfully investigated following vapor formation and identifying different Ni species