Hydrogen production, storage, transportation and key challenges with applications: A review

Summary Previous works indicated that aluminum hydroxide could be acted as catalyst to speed up the hydrolysis reaction of Al, and the catalytic activity of aluminum hydroxide is related to its microscopic properties. In this work, the effect of crystalline phases of aluminum hydroxide catalysts on Al hydrolysis is researched systematically. The results show that the hydrogen production performance of Al hydrolysis catalyzed by aluminum hydroxide with different crystalline phases is obviously different, and the catalytic activity of different aluminum hydroxides is in the order of boehmite > bayerite > gibbsite. A possible mechanism is given, which reveals that the surface hydroxyl groups of aluminum hydroxide act as anchoring sites for the adsorption of H2O molecules and decrease the dissociative adsorption energy of H2O molecules on aluminum hydroxides surface, promoting the hydrolysis reaction of Al. Consequently, the difference in catalytic activity of aluminum hydroxide with different crystalline phases is attributed to the difference in surface hydroxyl group density. This study provides a new idea for the synthesization of aluminum hydroxide with excellent catalytic activity.

Section: Introductionmentioning

confidence: 99%

Effect of crystalline phases of aluminum hydroxide catalysts on Al‐water reaction

Gai

Zhang

Yang³

et al. 2020

“…MOFs possess incredibly high H 2 adsorption capacities at high pressures and cryogenic temperatures . However, very low H 2 sorption capacities can be achieved at 298 K and low pressures .…”

Section: Introductionmentioning

confidence: 99%

“…5,14,[19][20][21] MOFs possess incredibly high H 2 adsorption capacities at high pressures and cryogenic temperatures. 5,[22][23][24] However, very low H 2 sorption capacities can be achieved at 298 K and low pressures. 25,26 These low H 2 sorption capacities have been due to weak van der Waals interactions between H 2 molecules and the surface.…”

Section: Introductionmentioning

confidence: 99%

Engineering MIL‐88B crystallites for enhanced H ₂ uptake capacity: The role of ultramicropores

Yurduşen

Yürüm

2019

Summary In this study, a strategy that optimizes the pore size to enhance the adsorbed H2 amount (at 298 K) is investigated. Pore size and ultramicropore fraction (ultramicropore volume/total pore volume) were controlled by Fe:TPA ratio. The highest H2 adsorption capacity of 0.47 wt% (298 K and 7.6 bar) belongs to MIL‐88B‐3, which is higher than those of reported metal‐organic frameworks (MOFs) (MIL‐100, MIL‐101 [Cr], HKUST‐1, MOF‐5, and ZIF‐8). The enhanced H2 sorption capacity (1.96 times) is a consequence of the high fraction (89%) and volume (0.22 cm3/g) of ultramicropores with pore diameters of 0.6 nm. Our results demonstrate that pore size, fraction, and volume of ultramicropores control the amount of H2 adsorbed also at 298 K. With the use of perturbation assisted nanofusion synthesis strategy that introduces textural pores to the pore structure, a Brunauer‐Emmett‐Teller (BET) surface area higher than those of reported MIL‐88Bs has been achieved, and a strategy to synthesize MOFs with enhanced H2 sorption capacities is suggested.

“…In this context, it is very crucial to find better pathways to produce H 2 enough to meet this strong demand. Methane steam reforming (MSR) is currently being commercially used for H 2 production because of its high efficiency and low levelized cost of H 2 (LCOH) compared to other methods like oil‐based H 2 production, coal gasification, and water electrolysis . Moreover, natural gas (NG) made up mostly of methane (CH 4 ) has been considered as being more eco‐friendly than conventional fossil fuels .…”

Section: Introductionmentioning

confidence: 99%

“…Methane steam reforming (MSR) is currently being commercially used for H 2 production 3,4 because of its high efficiency and low levelized cost of H 2 (LCOH) compared to other methods like oil-based H 2 production, coal gasification, and water electrolysis. 5,6 Moreover, natural gas (NG) made up mostly of methane (CH 4 ) has been considered as being more eco-friendly than conventional fossil fuels. 7 The MSR technology accounts for approximately 48% of global H 2 production, as shown in Figure 2, 8,9 and is a well-known process consisting of MSR (Equations 1 and 3) and high-and low-temperature water gas shift reaction (WGSR; Equation 2).…”

mentioning

confidence: 99%

Cost‐competitive methane steam reforming in a membrane reactor for H ₂ production: Technical and economic evaluation with a window of a H ₂ selectivity

Lee

Lim

2019

Summary Techno‐economic viability studies of employing a membrane reactor (MR) equipped with H2 separation membranes for methane steam reforming (MSR) were carried out for H2 production in Korea using HYSYS®, a well‐known chemical process simulator, including economic analysis based on itemized cost estimation and sensitivity analysis (SA). With the reaction kinetics for MSR reported by Xu and Froment, the effect of a wide range of H2 selectivity (10‐10,000) on the performance in an MR was investigated in this study. Because of the equilibrium shift owing to the Le Chatelier's principle, great performance of enhancement of methane conversion ( XCH4) and H2 yield and reaction temperature reduction was observed in an MR compared with a packed‐bed reactor (PBR). A window of a H2 selectivity from 100 to 300 is proposed as a new criterion for better MR performance of MSR depending on potential applications from in‐depth analysis of XCH4 and H2 yield enhancements, a H2 purity, and temperature reduction. In addition, economic analysis to evaluate the feasibility of an MR technology for MSR was carried out focusing on a levelized cost of H2 based on itemized cost estimation of capital and operating costs as well as SA. Techno‐economic assessment showed 36.7% cost reduction in an MR compared with a PBR and revealed that this MR technology can be possibly opted for a cost‐competitive H2 production process for MSR.