Methanol Hydrogen Research Articles

Direct ink writing of hierarchical porous SiC ceramics as catalyst support for hydrogen production

Due to the tunable porosity at multiple scales, hierarchical porous ceramics feature large specific surface area and excellent heat and mass transfer performance, which can effectively improve the catalytic reaction performance. This paper presents a method to fabricate SiC scaffolds with regular and hierarchical pore structures by direct ink writing (DIW) combined with sacrificial template technology, which can be used as methanol steam reforming (MSR) microreactor catalyst supports. Through printing along a defined path, primary pores with a regular pore structure were created. After sintering, the sacrificial template was removed and secondary pores appeared. Four different types of hierarchical porous SiC scaffolds were successfully prepared and the pore structure, total porosity, linear shrinkage and compressive strength of these scaffolds were investigated. The catalyst coating was then loaded onto the scaffold, and the microstructure characterization showed that the pore structure would not be damaged and blocked. Finally, the hydrogen production experiments were carried out on the MSR microreactor, and the results showed that the support with larger and denser secondary pores had the best fluid flow and hydrogen production characteristics. At the temperature of 280 °C and the gas hourly space velocity (GHSV) of 30000 ml g−1 h−1, the methanol conversion and hydrogen production of the best support can reach 90.95 % and 44.96 ml/min, respectively.

Influence of water‐methanol injection and turbocharging on the performance of a hydrogen‐fueled spark ignition engine

AbstractThis article presents a study that compares the performance and emission characteristics of a four‐stroke, four‐cylinder spark ignition (SI) engine fueled by gasoline and neat hydrogen. The engine was equipped with turbocharging to optimize ignition timing for power boosting and vaporized water–methanol injection to reduce emissions. Engine tests were conducted at speeds ranging from 2000 to 6000 rpm, with a fixed intake pressure and varying quantities of hydrogen and spark advance timings. The study compared the results of non‐turbocharged and turbocharged engines with water–methanol injection in terms of combustion, performance, and emissions. The findings showed that the turbocharged water–methanol hydrogen operation had a higher brake thermal efficiency (BTE) than its counterpart, while the brake power of the hydrogen engine operation increased with turbocharging but slightly decreased with water–methanol injection. Additionally, volumetric efficiency improved by 7% for turbocharged and 4% for water‐injected hydrogen engine operation compared to the counterpart. The cylinder pressure for turbocharging with water–methanol operation yielded 16.32% higher compared with counterpart gasoline engine operation. Finally, nitrogen oxides (NOx) emissions were reduced with turbocharging and water–methanol injection compared to the counterpart non‐turbocharged hydrogen engine operation.

Hybrid Acid/Base Electrolytic Cell for Hydrogen Generation and Methanol Conversion Implemented by Bifunctional Ni/MoN Nanorod Electrocatalyst.

Combining the methanol oxidation reaction (MOR) and hydrogen evolution reaction (HER) within an integrated electrolytic system may offer the advantages of enhanced kinetics of the anode, reduced energy consumption, and the production of high-purity hydrogen. Herein, it is reported the construction of Ni─MoN nanorod arrays supported on a nickel foam substrate (Ni─MoN/NF) as a bifunctional electrocatalyst for electrocatalytic hydrogen production and selective methanol oxidation to formate. Remarkably, The optimal Ni─MoN/NF catalyst displays exceptional HER performance with an overpotential of only 49mV to attain 10mAcm-2 in acid, and exhibits a high activity for MOR to achieve 100mAcm-2 at 1.48V in alkali. A hybrid acid/base electrolytic cell with Ni─MoN/NF electrode as anode and cathode is further developed for an integrated HER-MOR cell, which only requires a voltage of 0.56V at 10mAcm-2 , significantly lower than that of the HER-OER system (0.70V). The density functional theory studies reveal that the incorporation of Ni effectively modulates the electronic structure of MoN, thereby resulting in enhanced catalytic activity. The unique combination of high electrocatalytic activity and excellent stability make the Ni─MoN/NF catalyst a promising candidate for practical applications in electrocatalytic hydrogen production and methanol oxidation.

Dissecting ZnOX/Cu interfacial self-encapsulation and methanol-induced strong metal-support interaction of the highly active alloyed CuZn and ZnO for methanol steam reforming

A highly durable non-noble metal catalyst like copper for high-temperature methanol steam reforming is necessary for a compact hydrogen reactor. Herein, deactivation of copper-based catalysts with strong metal-support interaction is extremely sluggish even at 550 °C when using a selective chemical reduction approach paired with various induced activation procedures. The adsorbate methanol could enhance the migration of ZnOx onto the Cu and increase the number and electronic modulation of high-activity CuZn alloy sites. The Zn pre-deposited on the Cu surface induces continuous morphology and structural reorganization of the catalytic surface, which constantly refreshes the catalyst surface. The adsorbate methanol led to abundant CuZn alloy-ZnO synergism, which sped up the dissociation of·H2O and the dehydrogenation of *CH3O in accordance with the density functional theory and, ultimately, exhibited the highest methanol conversion (99.55 %) and hydrogen yield (97.73 %) compared to the hydrogen induction.

Thermal coupling of methanol steam reforming and hydrogen combustion to produce fuel cell hydrogen: A comparative theoretical study between membrane and hydrogen-recycled shell-and-tube reactors

Methanol steam reforming (MSR) is one the most interesting routes for production of fuel cell grade hydrogen. As this reaction is endothermic, its energy supply is one of the most important problems. In this line, recycling and burning the unconverted hydrogen exits from the exhaust of the fuel cells on the shell side of a shell-and-tube reactor (HR) has been suggested in the literature as one the energy supply solutions. In this work, the performance of a membrane-assisted shell-and-tube reactor (MR-HCO), in which part of the hydrogen produced by the MSR is continuously transferred to the shell side through the membrane layer and burned to supply energy, is investigated and compared with HR reactor. To this end, a set of heterogeneous 1D and 2D models are employed to model the shell and the tube sides of the reactors, respectively. The influence of air and steam-methanol feed hourly space velocities on maximum combustion temperature and methanol conversion are examined. It is observed that the MR-HCO has higher methanol conversion, hydrogen flow, and thermal efficiency, while lower CO concentration compared with the HR reactor. Furthermore, the MR-HCO showed a good potential to control the shell temperature rise and prevent hot spots.

Reactant Transport Engineering Approach at Cathode to High Power Direct Methanol Hydrogen Peroxide Fuel Cell

The development of high-power fuel cells could advance the electrification of the transportation sector, including marine and air transport. Liquid-fueled fuel cells are particularly attractive for such applications as they obviate the issue of fuel transportation and storage. Herein, we report a direct methanol hydrogen peroxide fuel cell (DMHPFC) for high-power propulsion applications that delivers 0.8 W cm2 peak power density by using a pH gradient-enabled microscale bipolar interface (PMBI) to effectively meet the incongruent pH requirements for methanol oxidation/peroxide reduction reactions.DMHPFCs are an important alternative to hydrogen-fed polymer electrode membrane fuel cell (PEMFCs) and anion exchange membrane fuel cells (AEMFCs) due to methanol’s high energy density compared to that of hydrogen and superior kinetics of hydrogen peroxide reduction reaction as compared to Oxygen. A unit volume of Hydrogen gas stored at a pressure of approximately 69 MPa corresponds to volume-specific energy density of roughly 2.1 kWh/l while 39% volume of aqueous methanol and 41% volume of aqueous hydrogen peroxide corresponds to volume-specific energy density of 9.2 kWh/l. So, DMHPFC’s energy density is approximately four times higher than hydrogen fuel cell’s energy density and is comparable to gasoline which contains roughly 9.2 kWh/l of available bond energy. The theoretical potential for Methanol oxidation reaction (MOR) in basic medium is lower than that in an acidic medium (-0.78 V vs. -0.02 V) and the theoretical potential for the Hydrogen peroxide reduction reaction (HPRR) is higher than that for oxygen reduction (1.77 V vs. 1.23 V in acidic medium). This results in the highest theoretically possible cell voltage for cells with alkaline anodes and acidic cathodes. We achieved sustained operation of the DMHPFC with an alkaline anode and an acidic cathode by incorporating our pH-gradient-enabled microscale bipolar interface (PMBI).However, the system exhibits a relatively low Faradaic efficiency of 50% due to the parasitic evolution of O2 by the decomposition of H2O2. The O2 evolution results in a mixed potential at the cathode due to the occurrence of both the HPRR (E0 = 1.77 V versus standard hydrogen electrode [SHE]) and the oxygen reduction reaction (ORR); (E0 = 1.23 V versus SHE), lowering the overall cell potential. The O2 surface coverage reduces the available sites for the HPRR, effectively deactivating the catalyst. Electrocatalysts exhibiting a combination of high HPRR activity and selectivity (by inhibiting H2O2 decomposition, and hence inhibiting ORR) would result in higher faradic efficiency and have been the subject of sustained interest. Here, we examine an alternate reactant-transport engineering approach to improve the overall cell potential and cell performance of the DMHPFC. Our reactant-transport engineering approach has examined the impact of reactant flowrate, flow velocity, residence time, and flow regime (via the Reynolds number ([Re]) on DMHPFC performance. Balancing the competing demands of high residence time to improve Hydrogen peroxide reduction reaction (HPRR) rates with high flowrates to detach adsorbed O2, we identify a critical Re and Damkholer number (Da) to efficiently exclude O2 gas bubbles while maintaining large current densities during the operation of a DMHPFC. Reactant-transport engineering of the cathode flow field architecture and fuel flowrates mitigates parasitic hydrogen peroxide decomposition and oxygen reduction reactions and lessens cathode passivation by oxygen bubbles. DMHPCs fulfilling these criteria provide a power density of >500 mW cm-2 at 1.0 V compared to state-of-the-art polymer electrolyte membrane fuel cells (PEMFCs) that typically operate at 0.75 V. The high peak power density of 800 mW cm-2 at 1.1 V may offer a pathway to reduce fuel cell stack size for propulsion applications. Our work paves the way for such other liquid fuel cells with hydrogen peroxide as the oxidant and enabled with PMBI resulting in significantly improvement in the performance. Figure 1

Nickel molybdate nanorods synthesized on carbon cloth as an electrocatalyst for methanol oxidation and hydrogen evolution reactions

In this report, the nickel molybdate (NiMoO4) nanorods were grown on carbon cloth (CC) with an average length of 3 µm and a diameter of 130 nm. The NiMoO4/CC demonstrated a lower onset potential of 0.553 V vs. Hg/HgO at 10 mA/cm2 for methanol oxidation reaction (MOR). In addition, the electrocatalyst showed notable cyclic stability, where the onset potential attained 0.585 and 0.616 V vs. Hg/HgO at 10 mA/cm2 during the 250th and 1000th cycles, respectively. In the hydrogen evolution reaction (HER), the NiMoO4/CC exhibited good performance with an overpotential of −0.517 V vs. RHE at 10 mA/cm2, the Tafel slope of 144 mV/dec, and a turnover frequency of 1.298H2/active site. The higher active sites (2.594 × 1017 cm2) and high electrochemical surface area (94.63 cm2) of NiMoO4/CC electrocatalyst exhibited stable and efficient MOR and HER performances.

Experimental Investigation on Converting the Acid Gas of an HDS Unit to High-Value Products by Methanol Thiolation: Case Study

The possibility of using acid gas as feedstock in methanol thiolation reaction was examined with K2O/WO3/γ-Al2O3 catalysts and the effect of impurities on H2S conversion and product distribution was evaluated in this paper. The results compared with the case using pure H2S as feedstock. Three samples of catalysts were synthesized by incipient wetness impregnation. The catalysts are characterized by Brunauer–Emmett–Teller, X-Ray powder Diffraction, and NH3- Temperature programmed desorption methods. Catalytic tests were performed in a fixed-bed flow reactor for an acid gas with 12.2% mol. H2S. Dimethyl sulphide (DMS) and methanethiol are produced through a methanol thiolation reaction and hydrogen is produced by a hydrocarbon reforming reaction. The catalyst with the lowest acidity showed the best results. H2S in acid gas converted about 78.6%. The yields were reported about 74.8% and 3.8% for DMS and methanethiol respectively. The amount of hydrogen increased by more than 200% in the reactor outlet.

Aqueous phase conversion of CO2 into acetic acid over thermally transformed MIL-88B catalyst

Sustainable production of acetic acid is a high priority due to its high global manufacturing capacity and numerous applications. Currently, it is predominantly synthesized via carbonylation of methanol, in which both the reactants are fossil-derived. Carbon dioxide transformation into acetic acid is highly desirable to achieve net zero carbon emissions, but significant challenges remain to achieve this efficiently. Herein, we report a heterogeneous catalyst, thermally transformed MIL-88B with Fe0 and Fe3O4 dual active sites, for highly selective acetic acid formation via methanol hydrocarboxylation. ReaxFF molecular simulation, and X-ray characterisation results show a thermally transformed MIL-88B catalyst consisting of highly dispersed Fe0/Fe(II)-oxide nanoparticles in a carbonaceous matrix. This efficient catalyst showed a high acetic acid yield (590.1 mmol/gcat.L) with 81.7% selectivity at 150 °C in the aqueous phase using LiI as a co-catalyst. Here we present a plausible reaction pathway for acetic acid formation reaction via a formic acid intermediate. No significant difference in acetic acid yield and selectivity were noticed during the catalyst recycling study up to five cycles. This work is scalable and industrially relevant for carbon dioxide utilisation to reduce carbon emissions, especially when green methanol and green hydrogen are readily available in future.

Brief research report optimization of catalyst porosity arrangements for hydrogen production in microchannel reactors by methanol reforming

Optimization of catalyst porosity arrangements is carried out for hydrogen production through computational modeling of a thermally integrated microchannel reactor. The reactor has parallel flow channels for conducting simultaneous oxidation and reforming reactions. Numerical simulations are performed under a variety of velocity conditions to evaluate the effect of reforming catalyst porosity arrangement on the transport phenomena in the reactor system. The oxidation catalyst has a uniform porosity, and the porosity range of the reforming catalyst is from 30 to 70 percent. The porosity is uniform in each segmented region and the overall porosity is maintained 50 percent. The heat and mass transfer issues for the reactor system are highly complex. Performance comparisons are made in terms of methanol conversion, hydrogen yield, and heat of reaction between these porosity cases under different inlet velocity conditions. Dimensionless Nusselt and Sherwood number analyses are performed to understand the underlying cause for the performance difference. The dimensionless numbers in transport phenomena are principally analyzed to understand how important the transverse transport components are. The results indicate that optimization of catalyst porosity arrangements is required for thermal matching purposes. The optimum porosity arrangement depends upon the flow rates. The catalyst porosities must be configured to improve the kinetics in the upstream or downstream sections of the reactor so that the endothermic and exothermic processes are thermally matched. While advantages can be realized by using the two-segment design, the three-segment design yields no advantage. The processes of transverse transport are of great importance to the chemical reactions.

Transition metal chloride catalyzed methanol gasification in supercritical water: Experimental and DFT studies

Experimental analysis and density functional theory (DFT) calculation were performed on methanol gasification catalyzed by transition metal chlorides (CdCl2, CuCl2, FeCl3, and NiCl2) in supercritical water. The reaction temperatures (550–625 °C), residence times (6–60 s), and catalyst concentrations (0.00025–0.001 mol L−1) were experimentally investigated using a continuous reactor. Non-catalytic gasification of methanol produced the H2 yield of 0.64 mol mol−1 and gasification efficiency (GE) of 28.42 wt%, while the addition of 0.0005 mol L−1 transition metal chlorides contributed to significantly improved H2 yield and GE of 1.17–1.16 mol mol−1 and 61.13–106.16 wt% at 575 °C, respectively. The water molecules decrease the overall energy barrier of methanol decomposition pathways to promote methanol hydrogenation by forming intermolecular hydrogen bonds. Different transition metal cations form coordinate bond force with the O atom of the hydroxy group, causing a 20.5–41.1% reduction in the energy barrier of methanol oxidation and promoting methanol decomposition.

Non-Phenomenological Description of the Time-Resolved Emission in Solution with Quantum-Classical Vibronic Approaches-Application to Coumarin C153 in Methanol.

We report a joint experimental and theoretical work on the steady-state spectroscopy and time-resolved emission of the coumarin C153 dye in methanol. The lowest energy excited state of this molecule is characterized by an intramolecular charge transfer thus leading to remarkable shifts of the time-resolved emission spectra, dictated by the methanol reorganization dynamics. We selected this system as a prototypical test case for the first application of a novel computational protocol aimed at the prediction of transient emission spectral shapes, including both vibronic and solvent effects, without applying any phenomenological broadening. It combines a recently developed quantum-classical approach, the adiabatic molecular dynamics generalized vertical Hessian method (Ad-MD|gVH), with nonequilibrium molecular dynamics simulations. For the steady-state spectra we show that the Ad-MD|gVH approach is able to reproduce quite accurately the spectral shapes and the Stokes shift, while a ∼0.15 eV error is found on the prediction of the solvent shift going from gas phase to methanol. The spectral shape of the time-resolved emission signals is, overall, well reproduced, although the simulated spectra are slightly too broad and asymmetric at low energies with respect to experiments. As far as the spectral shift is concerned, the calculated spectra from 4 ps to 100 ps are in excellent agreement with experiments, correctly predicting the end of the solvent reorganization after about 20 ps. On the other hand, before 4 ps solvent dynamics is predicted to be too fast in the simulations and, in the sub-ps timescale, the uncertainty due to the experimental time resolution (300 fs) makes the comparison less straightforward. Finally, analysis of the reorganization of the first solvation shell surrounding the excited solute, based on atomic radial distribution functions and orientational correlations, indicates a fast solvent response (≈100 fs) characterized by the strengthening of the carbonyl-methanol hydrogen bond interactions, followed by the solvent reorientation, occurring on the ps timescale, to maximize local dipolar interactions.

NUMERICAL SIMULATION STUDY ON THE REACTION PERFORMANCE OF A METHANOL STEAM REFORMING TO HYDROGEN MICROREACTOR

Hydrogen has received widespread attention as a new clean energy in order to reduce the carbon emissions of fuel vehicles. This paper studies a tubular microreactor based on methanol steam reforming. Methanol and steam are mixed in proportion and the chemical reaction takes place in a porous catalytic bed. For heating purposes, hot gas from the burner penetrates the reactor bed through heating tubes. Energy is supplied through the heating tubes to drive the endothermic reaction system. The microreactor is enclosed in an insulated jacket. In this paper, parameters such as methanol conversion and hydrogen concentration are evaluated by considering microreactor materials, heating gas temperature and flow direction, heating tube distribution, pressure drop and reaction channel length. First of all, choosing a microreactor material with a smaller thermal conductivity can avoid excessive heat loss, and improve heat transfer performance. Increasing the heating gas temperature leads to an increase in the temperature of the reaction zone, thereby increasing the CH3OH conversion rate and H2 mass fraction. Changing the flow direction of the heating gas affects the reaction rate, but has little effect on the reaction result. Through the research on the distribution of the heating tubes, the results show that the hydrogen production rate is higher when the contact area between the heating tubes and the reaction zone is larger. Secondly, through the comparison of the data under different pressure drops, the best parameter [Formula: see text][Formula: see text]pa is obtained, and the CH3OH conversion rate is 80.6% at this time. Finally, increasing the length of the reaction channel can make the reaction more complete. For example, when the reaction channel length [Formula: see text][Formula: see text]m, the CH3OH conversion rate is as high as 83.7%.

Synthesis of PtAu Alloy Nanocrystals Supported on Three-Dimensional Carbon with Enhanced Electrocatalytic Properties

Sub-nanosized PtAu particles within three-dimensional carbon materials were obtained via a mercaptosilane-assisted preparation method. This strategy can effectively control the size of PtAu particles while avoiding the use of an additional carbon precursor. The as-synthesized three-dimensional carbon (3D carbon) material possesses excellent properties compared to other carbon materials. PtAu particles on three-dimensional carbon (PtAu/3D carbon) exhibited superior activities for methanol oxidation and hydrogen evolution reactions compared to Pt/3D carbon and a commercial Pt/Carbon (Pt/C) catalyst. Specifically, the methanol peak current density on PtAu/3D carbon was almost 2.3 times higher than that of Pt/3D carbon and 1.9 times higher than that of commercial Pt/C. The Tafel slopes of PtAu/3D carbon, Pt/3D carbon, and the commercial Pt/C were approximately 112, 124, and 106 mV dec−1, respectively, demonstrating that electrochemical desorption is the rate-limiting step in the hydrogen evolution reaction of the as-synthesized catalysts.

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

CuO–ZnO (CZ) and CuO–ZnO/TiO2 (CZT) catalysts have been prepared by co-precipitation, characterized by X-ray diffraction, surface area measurements and chemical analysis and tested in the combined methanol reforming reaction. Catalytic tests have been performed in the temperature range 200–400 °C with a GHSV = 55.000 h−1, after H2 reducing pretreatment at 250 °C or 450 °C. It is shown that nanocrystalline TiO2 influences the CuO–ZnO nanosized structure, reducibility and reactivity. TiO2 slightly increases ZnO crystallite size of the fresh catalyst. Moreover, it causes the CuO chemical reduction to nanosized Cu2O on exhaust catalyst pretreated in hydrogen at 250 °C, this improves the reaction with higher methanol conversion and hydrogen production. On the contrary, TiO2 reduces CuO to submicron Cu0 and greatly increases ZnO crystallite size on the exhaust catalyst pretreated in hydrogen at 450 °C, this treatment weakens the reaction, with lower methanol conversion and hydrogen production. In both cases, nanocrystalline TiO2 presence is able to decrease the CO formation: independently of the hydrogen pretreatment temperature. This ability of the nanocrystalline TiO2 is ascribed to the presence of the oxygen vacancies, which act as electron donors that contribute to hinder CO2 and H2 surface adsorption for steric, electrostatic and probabilistic factors.

Sustainable cement and clay support in Ni–Cu/Al2O3 catalysts for enhancing hydrogen production from methanol steam reforming

Sustainable cement-clay composite is used as the support of bimetallic Ni–Cu/Al2O3 catalysts for hydrogen production from methanol steam reforming (MSR) reaction. The results indicate that higher methanol conversion and hydrogen yield can be obtained using composite supported catalysts. The cement-clay composite possesses CO2 absorption capability, which can enhance MSR performance. In the cases of a large proportion of cement, the CO2 concentration in the product is decreased by 1–2% where methanol conversion and hydrogen yield are not reduced. By varying the catalyst compositions such as Ni content, Ni–Cu/Al2O3 loading, and the weight ratio of cement and clay, 100% methanol conversion can be achieved as Ni content and Ni–Cu/Al2O3 loading increase. However, the CO concentration also increases due to the enhanced reverse water gas shift reaction. The results of the prepared 12 cement-clay-supported cases show the best performance with methanol conversion of 100%, hydrogen yield of 2.85 mol·(mol CH3OH)−1, and CO concentration of 5.90%. The scanning electron microscope images indicate no sintering of the spent catalyst, and the thermogravimetric analysis shows low coke formation on the catalyst surface. Overall, cement-clay replacing metal components in catalysts can efficiently reduce costs and intensify hydrogen production.

A Comparative Study of the Synthesis and Hydrolysis of sym-Triaminobenzene Homologues

Here, we investigated the synthetic processes for the methyl derivatives of sym-triaminobenzene and phloroglucinol, the essential chemical reactants coming into use in the production of dyes and pigments, and medicinal drugs for different purposes. The most eco-benign process for the synthesis of triamino derivatives involves the catalytic hydrogenation of corresponding nitroarenes. The present study investigated the hydrogenation of 2,4,6-trinitrotoluene, 2,4,6-trinitroxylene, and 2,4,6-trinitromesitylene over a Pd catalyst. A 1% Pd/Sibunit catalyst was found to be preferable to the 5% analogue with a preserved palladium loading because it shortens the reaction time and provides a higher yield of the target product. The hydrogenation in methanol (or mixed methanol/toluene) at 50-55 °C and 0.5 MPa pressure produced 2,4,6-triaminotoluene, 2,4,6-triaminoxylene, and 2,4,6-triaminomesitylene, which were isolated as sulfuric acid salts in 98, 91, and 97% yields, respectively. The hydrolysis process of the resultant salts was examined, and conditions leading to mono-, di-, and trimethyl derivatives of phloroglucinol (90, 77, and 82%, respectively,) were identified. The hydrogenation of the trinitrobenzene homologues in mixed 7:1 (v/v) acetone/water, followed by hydrolysis to the respective polyphenols, was explored. A successful result was achieved only for 2,4,6-trinitrotoluene. The catalyst activity was shown to decline negligibly throughout 10 cycles of reuse. 2-Methylphloroglucinol was synthesized in a high yield ranging from 85 to 91% calculated as 2,4,6-trinitrotoluene.

Process Design and Techno-Economic Assessment of biogenic CO2 Hydrogenation-to-Methanol with innovative catalyst

A small-scale 10 ton per day methanol (MeOH) synthesis plant, from CO2 and hydrogen, is designed and simulated with Aspen Plus and a techno-economic analysis is conducted. The e-fuel (MeOH) is produced in a conventional fixed bed reactor featuring an innovative Cu/Zn/Al/Zr catalyst, converting biogenic CO2 from a biogas upgrading plant with H2 produced by a grid powered PEM electrolyzer. The process is thermally autonomous as a result of heat integration and combustion of purged unconverted reactants. A sensitivity analysis is carried out in order to evaluate and compare the impact of the different technical (purge fraction, Gas Hourly Space Velocity and Pressure of the methanol synthesis) and economic parameters (Capital Charge Factor, electricity and H2 cost) on the Levelized Cost Of Methanol (LCOM). Results show that, although the energy efficiency is greater (47.4 % electricity to methanol conversion) in the scenario with “self-sufficiency” in which all the net heat required by the process is provided by off-gas streams, the case with the highest profitability is the one with maximum methanol yield and, therefore, minimum purge and non-zero thermal energy import (provided by a biogas boiler). The best case scenario features a LCOM equal to 1,361 €/tonMeOH, with a GHSV of 7,500 h−1 and synthesis reactor operating at 70 bar, 250 °C. H2 production cost is the key variable and shall be reduced from the base case value of 5.8 €/kgH2 to 1.6 €/kgH2 in order to make the CO2 to methanol plant competitive with a MeOH market price of 550 €/tonMeOH; synthesis reactor operating conditions have more limited impact from a cost perspective, except for the purge fraction that shall be optimized to maximize the amount of MeOH produced.

A methanol autothermal reforming system for the enhanced hydrogen production: Process simulation and thermodynamic optimization

Methanol autothermal reforming is a potential way to produce hydrogen that can be used for vehicle power batteries like PEMFC. Combining a reformer with a combustor to produce substantial hydrogen is promising, but the challenge of heat transfer efficiency between the reformer and combustor must be considered. Furthermore, the complexity of the system structure is not conducive to its large-scale operation level. In this paper, a novel methanol autothermal reforming hydrogen production system without catalytic combustion was built and developed, aiming to produce hydrogen-rich gas with low CO concentration. Process simulation and thermodynamic optimization on the target system were detailedly performed using Aspen Plus software and parameter sensitivity analysis methods. In addition, a methanol autothermal reforming hydrogen production system using catalytic combustion was taken as the reference system. The results indicated that the novel system could achieve a self-sustaining operation by the coupled methanol partial oxidation and steam reforming. And the product gas contained very low CO concentration (<10 ppm) due to the combined effects of water-gas shifting and CO preferential oxidation reactions. It was verified that under the maximal exergy efficiency condition, the exergy efficiency of the novel system is not significantly improved compared with the reference system, but the hydrogen yield is increased by about 27.65%, the thermal efficiency is increased by about 17.51%, and the exergy loss when generating unit molar H2 is reduced by 20.53 kJ/mol; Under the condition of maximum hydrogen yield, the indicators of the novel system also perform better. Notably, the reformer is the main exergy loss source in the novel system, which provides a theoretical basis for further optimization of parameter configuration. This work will be beneficial to researchers who study the miniaturization design of the integrated system of methanol hydrogen production coupled vehicle power battery.

Cost assessment of alternative fuels for maritime transportation in Ireland

In this study, we investigated the cost-effectiveness of four alternatives: Liquified Natural Gas (LNG), methanol, green hydrogen, and green ammonia, for the case of top 20 most frequently calling ships to Irish ports in 2019, through the Net Present Value (NPV) methodology, incorporating the benefits incurred through saved external, carbon tax and conventional fuel costs. LNG had the highest NPV (€6,166 million), followed by methanol (€1,705 million) and green hydrogen (€319 million). Green ammonia utilisation (as a hydrogen carrier) looks inviable due to higher operational costs, resulting from its excessive consumption (i.e., losses) during the cracking and purifying processes and its lower net calorific value. Green hydrogen remains the best option to meet future decarbonisation targets, although, a further reduction in its current fuel price (by 60%) or a significant increment in the proposed carbon tax rate (by 275%) will be required to improve its cost-competitiveness over LNG and methanol.