Water Adsorption Capacity Research Articles

CELLULOSE NANOFIBERS OF OIL PALM BIOMASS IN ALGINATE-BASED MEMBRANES FOR WATER-ETHANOL MIXTURE SEPARATION

TEMPO-oxidized cellulose nanofibers (TOCNs) from waste of oil palm empty fruit bunches (OPEFB) were integrated into an alginate matrix to increase the capacity of the alginate membrane for water-ethanol separation. The membrane composed of the alginate matrix and TOCNs was characterized in terms of its morphological, physical-mechanical properties and performance in the separation of water-ethanol suspensions, with ethanol concentrations in the suspension of 10% and 20%. Other alginate membranes integrated with commercial TOCNs from wood were also prepared and tested for comparison. The results showed that the addition of TOCNs (made from wood and OPEFB waste) to the alginate matrix improved the water adsorption capacity of the membrane. The water adsorption capacity of the alginate membranes with wood-derived TOCNs, OPEFB-derived TOCNs and alginate only was 78%, 87% and 66%, respectively. The flux capacity of the alginate membrane, integrated with OPEFB-derived TOCNs, was higher than that of the alginate membrane alone, but lower than that of the alginate membrane integrated with wood-derived TOCNs. This study showed the utilization of nanocellulose from palm oil biomass waste can be considered to improve the physical-mechanical properties of alginate-based membranes used for various applications, including filtration.

Control over the Hydrophilicity in the Pores of Covalent Organic Framework Membranes for High-Flux Separation of Dyes from Water

Membrane separation is making substantial contributions to water purification. Particularly important is the pore-size control designed for molecular sieving. Regarding water permeation, filtration experiments accentuate the importance of hydrophilic pores in enhancing the water adsorption capacity, while hydrophobic pores enable low-friction water diffusion. To reach both the criteria, we herein precisely design the pore metrics and pore functionalities to prepare a covalent organic framework (COF), termed TUS-46, membrane. Credited with pore sizes befitting for size-selective molecular exclusion and negative electrostatic pore walls, the TUS-46 COF membrane shows excellent rejection performance toward anionic dyes. Attributed to the free aldehyde functionalities in the framework resulting from unbalanced stoichiometry, the TUS-46 COF membrane also shows a 10-fold higher water permeance compared to the analogue COF membrane without free aldehyde functionalities. In particular, the in situ construction of hydrophilic nanospaces partaking in high water uptake and hydrophobic nanospaces facilitating fast water diffusion in a single COF structure endows the TUS-46 membranes with unprecedentedly high water flux. The stoichiometric imbalance approach presented herein offers a different route to COF membrane fabrication and may impart with an unprecedented control handle on the permeability and separation selectivity of COF membranes.

In situ precipitated NiCo nanoparticles synergize with metaborate to promote hydrogen evolution and couple with urea oxidation to reduce overall water splitting potential

A novel NiCo nanoparticles anchored on Ni(Co)(BO2)2 are constructed via a simple redox reaction of NiCo LDH (layered double hydroxide) with NaBH4 which method avoids the Ni foam deformation caused by high temperature reduction or pyrolysis. The experimental and DFT (density functional theory) investigation reveal metaborate (Ni(Co)(BO2)2) exhibits a stronger water adsorption capacity than that conventional metal LDH, which is conducive to the occurrence of hydrogen adsorption in the next step, while NiCo (ΔGH* is closer to 0) is a more suitable hydrogen reaction site than Ni or Co, this synergistic effect of the two substances greatly promotes Volmer step for HER (hydrogen evolution reaction), thereby fundamentally improving HER. The existence of Co0 helps to generate more Ni0, and Co plays an electronic auxiliary role. The Ni0(Co0)-Ni(Co)(BO2)2/NF catalyst possesses small charge transfer resistance, large electrochemical surface area and good hydrophilicity. The Ni0(Co0)-Ni(Co)(BO2)2/NF catalyst exhibits a great application prospect with an overpotential of only 25 mV at a current density of 10 mA cm−2. Even at a large current density of 100 mA cm−2, the overpotential is 107 mV. At a current density of 10 mA cm−2, the voltages of OER (oxygen evolution reaction) and UOR (urea oxidation reaction) are 1.561 V (vs. RHE) and 1.353 V, respectively. Using Ni0(Co0)-Ni(Co)(BO2)2/NF as a bifunctional catalyst for HER and UOR, only 1.47 V can drive a current density of 10 mA cm−2. It is shown that the catalyst will greatly reduce energy consumption and decompose urea when coupling HER and UOR.

Dual hydrophobic modification on MIL-101(Cr) with outstanding toluene removal under high relative humidity

The volatile organic compounds (VOCs) removed in the presence of atmospheric moisture using metal-organic framework (MOF) MIL-101(Cr) powder had been grievously restricted by the need for powder shaping and poor moisture stability. In this study, a dual modification was employed to conquer these issues. We firstly crystallized MIL-101(Cr) on the inner surface of amine grafting macroporous polyacrylate (PA-NH2) spheres using an in-situ confined growth strategy. The average size of MIL-101(Cr) crystals decreased by 15 times by reducing the nucleation energy barrier through high surface energy induced by interface engineering and enrichment of precursor solution on the interior surface with nanoscale roughness of carrier. Further hydrophobic composite P-MIL-101(Cr)@PA-NH2 was subsequently empoldered with the adoption of chemical vapor deposition (CVD) by polydimethylsiloxane (PDMS). The static adsorption capacity of water on P-MIL-101(Cr)@PA-NH2 was greatly diminished by 87.39 %, which was attributed to the change in the way of clustering of water molecules. The breakthrough results of competitive adsorption also showed that the working capacity of hydrophobic composites was 6.3 times that of the pristine MIL-101(Cr) powder under the conditions of 1000 mg/m3 toluene and 50 % RH, while maintaining 81.1 % of the original adsorption capacity after being exposed to the humid atmosphere for 30 days, showing excellent structural stability and outstanding adsorption performance. The brilliant performance of the present adsorbent made it promising for practical application in VOC capture.

Crystal-to-Crystal Transformation Caused by Cation Exchange and the Difference in Electrochemical Properties of Three Coordination Polymers

In this study, we prepared three highly stable coordination polymers under hydrothermal conditions, {[Zn2(μ3-DBd)2(H2O)2]·H2O}n (1), {[Cd(μ4-DBd) (H2O)]·3H2O}n (2), and {[Pb(μ4-DBd)]}n (3). Interestingly, the crystal-to-crystal transformation could occur between 1 and 3 via means of cation exchange. 1 and 2 were two-dimensional structures and 3 was a three-dimensional structure. The structure of 2 contains a continuous hydrogen bond network, which can form an excellent hydrophilic channel. We explored the relationship between cation exchange-induced crystal-to-crystal transformation and water adsorption capacity, and proton conductivity. 1–3 exhibited excellent stability and temperature- and humidity-dependent proton conduction properties. Among these, the water adsorption capacity of 2 was 327.39 cm3·g–1, which was 8.14-fold and 39.23-fold than that of 1 and 3, respectively. The proton conductivity of 2 reached 1.67 × 10–4 S·cm–1 at 80 °C under 98% relative humidity, which was nearly 2 orders of magnitude higher than the proton conductivity of 1 and 3. All the results indicated that the continuous hydrogen bond network inside the structure was responsible for the transfer of proton and increased the proton conductivity of coordination polymers.

In-situ growth of ReS2/NiS heterostructure on Ni foam as an ultra-stable electrocatalyst for alkaline hydrogen generation

Improving water adsorption and hydrogen (H) atoms desorption capacities are critical issues for the hydrogen evolution reaction (HER) in alkaline media. Herein, a ReS2/NiS heterostructure was generated in situ on the surface of the nickel foam (NF) using a facile hydrothermal process. The combination of experimental and density functional theory (DFT) analyses revealed a charge transfer from NiS to ReS2, which directly promoted water adsorption on Ni sites in NiS as well as H desorption on S sites in ReS2. Moreover, the antioxidation capacity of the heterointerface in the catalyst improved. Therefore, the formed ReS2/NiS@NF delivered an excellent HER activity very close to that of commercial Pt/C at low current density with overpotential of 78 mV at 10 mA/cm2 while remarkably outperforming Pt/C at high current densities. The ReS2/NiS@NF also exhibited remarkable stability at 150 mA/cm2. This work provides a strategy for designing excellent electrocatalysts based on NiS.

A modified Guggenheim-Anderson-Boer model for analyzing water sorption in coal

The presence of water can alter the mechanical properties of coal, which may not only cause roof falls during the coal mining process but also affect the hydraulic fracturing of coalbed methane (CBM) reservoirs. The nature of water adsorption properties in unconventional reservoir rocks has been the subject of several recent papers. However, the adsorption properties and adsorption mechanism of water in coal have not been thoroughly investigated. In this study, we carried out water vapor sorption experiments on four coal samples of different maturities. We found no linear relationship between maturity and water adsorption capacity. Furthermore, we proposed that the water adsorption mechanism in coal can be divided into two types: attached to oxygen functional groups and pore filling, which occur in hydrophilic pores and hydrophobic pores, respectively. Based on the above hypothesis, a modified Guggenheim-Anderson-Boer model was proposed to interpret water adsorption isotherms. It was concluded that the differences in the water adsorption characteristics of different coals under high humidity conditions were caused by the pore volume and the proportion of hydrophilic pores. We further analyzed the influence mechanism of water adsorption on methane adsorption under high relative humidity conditions. We found that the influence of water adsorption on methane adsorption in coal can be attributed to the water adsorption amount and proportion of hydrophilic pores.

Influence of polypropylene residues on the physico-mechanical and water-resistance properties of gypsum plasters

The main objective of the present research is to determine the feasibility of using polypropylene (PP) waste to produce eco-friendly gypsum-based composites. Four different replacement levels of plastic waste were selected for analysis - 2.5%, 5%, 7.5% and 10% by weight of gypsum. The first stage of the experimental campaign consisted of analysing the resulting composites based on density, mechanical performance (flexural and compressive strength) and surface hardness (Shore C). In the second stage, samples were evaluated based on their water absorption by capillary action or exposing them to continuous moisture in a wet chamber, and water resistance by subjecting them to several wetting-drying cycles. After that, scanning electron microscopy (SEM) analyses were carried out to evaluate the quality of the cohesion at the interfacial transition zone (ITZ) between the PP waste particles and the gypsum matrix. The results showed equivalent compressive strength and even a slight improvement (up to ∼9% when using 2.5% of PP waste when compared to the control material) most likely due to the greater compactness from the improved particle size distribution. In addition, a considerable reduction in water absorption and retention capacity was observed, due to the increasing incorporation of recycled PP into the gypsum matrix. The new PP-containing composites subjected to water absorption by capillary action and continuous moisture tests presented lower water absorption and adsorption capacity, wherein specimens with 10% of PP waste showed a decline of up to ∼37% when compared to the reference material. It was generally observed that the waste material can be considered as a viable partial substitute to the current commercial gypsum for the production of gypsum plasterboards.

Magnetic Stuffed Bun-Structured Metal-Organic Framework Monoliths with Noncompromised Accessible Pores and Highly Efficient Recycling Capability.

Development of industrially favorable metal-organic framework (MOF) monoliths is of paramount importance for their real-world applications. However, MOF monoliths prepared with the existing MOF shaping methods usually have seriously compromised accessible pores and suffer from inefficient and energy-intensive recycling, thereby greatly limiting their practical applications. We herein present a magnetic stuffed bun-structured MOF (mSBM) bead consisting of highly porous poly(vinyl alcohol) wraps stuffed with a binder-free powder mixture of UiO-66 and Fe3O4 nanoparticles. Such a unique structure and composition of the mSBM not only make its MOF component have a well-reserved crystal structure, surface area, and porosity and the corresponding accessible pores but also impart it with excellent localized magnetic induction heating (LMIH) capability that enables the sufficient heating and highly efficient recycling of the mSBM. These merits of mSBMs are further exemplified by assessing their atmospheric water adsorption and LMIH-driven water desorption performance. The mSBMs exhibit well-reserved atmospheric water adsorption capacities, up to 100% LMIH-driven water desorption, excellent reusability, and durability toward the practical applications. Our current work, therefore, demonstrates a new MOF shaping strategy to produce MOF monoliths with well-defined shapes, noncompromised accessible pores, and highly efficient recycling capabilities, paving a bright avenue to accelerate the practical applications of MOF monoliths.

Highly efficient adsorption desalination employing protonated-amino-functionalized MOFs

The MOFs (metal organic frameworks) namely MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) are found suitable for desalination and cooling applications. To improve both cooling and desalination performances, these MOFs were embedded with amino (–NH2) functional groups. For further improvement of water adsorption capacity and rates, the amino-functionalized MOFs can be protonated with hydrochloric acid (HCl). This article at first deals with the synthesis and characterization of protonated-amino-functionalized (NH3+Cl−) MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) MOFs. Secondly, under adsorption and desorption conditions, the H2O loadings on these adsorbents are evaluated from transient to steady states. The experimental results show that the protonation (NH3+Cl−) based MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) MOFs show the greater water distribution of 0.35, 0.31 and 0.4 kg/kg of MOFs. According to experimental results (heat exchanger performance, adsorption isotherms and kinetics data), the performance criteria such as specific cooling capacity (SCP), daily water production (SDWP) and coefficient of performance (COP) are evaluated for various desorption temperature (60 to 80°C) and cycle time (100 to 1000 s). The simulation results show a remarkable improvement in water production i.e., SDWP > 50 m3 desalinated water/t of adsorbents/day for protonated UiO-66 (Zr) MOFs. Additionally, the SCP improves from 0.006 to 0.72 kW/kg of MOFs.

Synthesis of urea-containing sodium alginate-g-poly(acrylic acid-co-acrylamide) superabsorbent-fertilizer hydrogel reinforced with carboxylated cellulose nanocrystals for efficient water and nitrogen utilization

A novel slow-release nitrogen fertilizer hydrogel nanocomposite was fabricated by in-situ free radical copolymerization between sodium alginate (SA), acrylic acid (AA), and acrylamide (AM) in an aqueous media using N, N’methylene bis-acrylamide (MBA) as a crosslinker, citric acid-functionalized cellulose nanocrystals (C-CNC) as a nanofiller and urea as a source of nitrogen. Several variables influencing the water absorbency of the fabricated hydrogels were studied and optimized. The optimized Hyd/C-CNC and Hyd/C-CNC/urea were fully characterized to determine their structure, thermal stability, and morphology. Swelling behavior in saline solutions such as (NaCl, CaCl2, and FeCl3) and at various pHs (2−12) as well as the swelling kinetics were investigated. The incorporation of functionalized cellulose nanocrystals into the hydrogel was very beneficial since it boosts the water absorbency from 260 ± 8 g/g for hydrogel without C-CNC to 316 ± 10 g/g for the hydrogel with 1.5 wt% of C-CNC. The soil experiment showed an enhanced soil water-retention capacity after the addition of 1 wt% of the Hyd/C-CNC polymer. The addition of urea confers to the Hyd/C-CNC material an enhanced water retention property and a slow-release nitrogen property. Under optimized conditions, the Hyd/C-CNC/urea had a total nitrogen amount of 13.66%, a high swelling degree (412 ± 4 g/g), and prolonged nitrogen release duration (20 days for complete N-release). Thus, the good water adsorption capacity, as well as the good slow-release fertilizer property, make this material a suitable water-saving material for agriculture applications.

Boron-doping nanoarchitectonics on three-dimensional carbon nanosheets with exaltation of hydrophilicity and conductivity for enhancing photocatalytic hydrogen evolution

Hydrogen evolution via dye-sensitized photocatalytic water reduction is a promising approach for storing solar energy due to high efficiency and good stability. The hydrophilic and electrical performances of sensitized matrix are critical for the reactant adsorption and photogenerated charge transport. Herein, theoretical simulation proves that the boron-doping nanoarchitectonics on three-dimensional carbon nanosheets (B-3DCNs) as a new-style sensitization matrix possesses a strong water adsorption capacity to show a stable disperse in water, as well as optimizes charge distribution to improve conductivity compared with pure material. So the boron dopants on the substrate surface can be used as an anchor for water and a booster for charge transfer. Based on the theoretical results, B-3DCNs with abundant and stable boron atoms is prepared by a solid-phase thermal doping technology using sodium borohydride as boron source. The hydrophilic and electrical properties of B-3DCNs is greatly optimized using a series of structural and performance testing, providing the prerequisite for large-scale applications in aqueous solution. Therefore, the constructed B-3DCNs/Pt photocatalyst displays a high photocatalytic hydrogen evolution rate under visible light in Eosin Y sensitized system, which is 5.9 and 2.3 times than the H2 evolved over bare Pt and 3DCNs/Pt.

Sorption-enhanced methane synthesis in fixed-bed reactors

Production of synthetic methane as a substitute for natural gas has been widely discussed as a means of long-term energy storage with the potential of CO2 neutrality. While the maximum conversion of catalytic CO2 methanation is limited by the highly exothermic and pressure-dependent nature of the Sabatier reaction, high conversion at low pressure could be achieved at laboratory scale through sorption enhancement. The transient nature of this process requires new reactor designs and process engineering for large-scale reactors. We investigated pellet bed reactors from a process and reactor engineering perspective, particularly in the context of upscaling. Our results show that heat generation in the reactor remains a major challenge for process performance and product purity. The bed temperature is coupled with the water adsorption capacity of the catalyst, which in turn affects the reactor capacity. Consequently, this has an impact on the dynamics of the coupled adsorption and reaction front with implications for the design of larger reactors. The results provide a comprehensive understanding of the process and a guide for reactor engineering.

High Sensitive Humidity Sensors Based on Biomass Ionogels

This work proposes humidity sensors based on ionic liquid loaded in situ crosslinked ionogels. Stable ionogels were constructed by the synergistic effect of k-carrageenan and gelatin to ensure the uniformly dispersion of ionic liquid, which is conducive to the stability of humidity sensors. The humidity sensitive electrolyte with different contents were introduced into the ionogels. By controlling the ratio of ionic liquid in the crosslinked ionogels, the optimal sensor exhibits a high sensitivity in the low humidity range (5% - 35% RH). The resultant sensors exhibit excellent repeatability, and possess good stability in long-term tests up to 60 days. The introduction of ionic liquid to the sensing film is beneficial for enhancing the water adsorption capacity and ionic conductivity, which is of great significance for high-performance humidity sensors.

Proximate composition and functional analysis of some polyherbal formulations as potential botanical candidates for antidiabetic screening: A Preliminary study

Polyherbal formulations improve therapeutic action while lowering single herb concentration, thereby reducing possible side reactions. Proximate composition and functional properties of tomato, garlic, and carrot formulations were studied. Fresh samples of the botanicals were collected, identified and authenticated. Equal amount of each sample (500 g) was weighed, shed-dried and crushed into fine powdered particles. The proximate composition and functional properties of each formulation were determined according to a standard assay guideline. The result on proximate composition analysis revealed a significant (p ˂ 0.05) higher moisture content of tomato and carrot formulations when compared to other formulations. The content of ash and crude protein were significantly (p ˂ 0.05) higher in all garlic containing formulations. The garlic formulation was observed to have lower fat content and greater carbohydrate content than all other formulations (p˂ 0.05). However, when compared to single formulations, all mixed formulations had significantly higher crude fiber content. Furthermore, there was a significant (p ˂ 0.05) variation in glucose adsorption capacity, oil adsorption capacity and water adsorption capacity among all the formulations. The outcome of this study have led us to conclude that employing safe combinations of these herbal formulations for the production of nutraceuticals is recommended.

Water adsorption performance of UiO-66 modified by MgCl2 for heat transformation applications

UiO-66 is a potential material for adsorption heat transformation (AHT) with high specific surface area, and excellent thermal and chemical stability. However, the low water adsorption capacity of UiO-66 in the low relative pressure range (0 < P/P 0 < 0.3) limits its application in AHT. We prepare the UiO-66 modified by MgCl2 through using the solvothermal method and impregnation method, and study their water vapor adsorption performances and heat storage capacities. Attributed to the extremely high saturated water uptake and excellent hydrophilicity of MgCl2, the water adsorption performance of UiO-66 is improved, although the introduction of MgCl2 reduces its specific surface area and pore volume. The water adsorption capacity at P/P 0 = 0.3 and the saturated water adsorption capacity of the UiO-66 (with MgCl2 content of 0.57 wt%) modified by the solvothermal method are 0.27 g/g and 0.57 g/g at 298 K, respectively, which are 68.8% and 32.6% higher than the counterparts of pure UiO-66, respectively. Comparing with pure UiO-66, the water adsorption capacity of the UiO-66 (with MgCl2 content of 1.02 wt%) modified by the impregnation method is increased by 56.3% and 14.0% at the same pressure, respectively. During 20 water adsorption/desorption cycles, the above two materials show high heat storage densities (∼ 1293 J/g and 1378 J/g). Therein, the UiO-66 modified by the solvothermal method exhibits the excellent cyclic stability. These results suggest that the introduction of an appropriate amount of MgCl2 makes UiO-66 more suitable for AHT applications.

Cost-effective and eco-friendly synthesis of MIL-101(Cr)-CS from chromium-containing sludge waste and its exploration of adsorption anddehumidification performance

In the context of a circular economy, there is an increasing need for more sustainable waste management solutions to recycle and utilize elements in waste. Chromium-containing sludge is a common and difficult to treat industrial waste, but there is currently no effective treatment method to recycle the “chromium resource” in it. On the other hand, the metal-organic framework material MIL-101(Cr) has high specific surface area and large pore volume, good thermal and chemical stability, usually analytically pure Cr(III) is used with the help of hydrofluoric acid (HF) which salt is prepared, and its preparation cost is high, and HF is toxic and harmful to the environment. Here, we report a new method for treating industrial chromium-containing sludge. The method uses the chromium in the chromium-containing sludge as the chromium source, and adopts X-ray diffraction (XRD), scanning electron microscope (SEM), infrared and pore size analysis. The experimental results show that the particle morphology of MIL-101(Cr)-CS synthesized from chromium-containing sludge as chromium source is similar to that of MIL-101(Cr)–HF prepared from analytical pure Cr(III). High specific surface area (2412 ​m2/g), large pore volume (1.83 ​m3/g). Furthermore, adsorption experiments show that MIL-101(Cr)-CS has a higher adsorption capacity for CO, CO2, and gaseous water, which makes it a potential candidate for some dehumidification devices and flue gas treatment. This work provides a new idea for the high-value utilization of “chromium resources” in chromium-containing wastes.

Photocatalytic Methane Conversion: Insight into the Mechanism of C(sp 3 )–H Bond Activation

Photocatalytic Methane Conversion: Insight into the Mechanism of C(sp ³ )–H Bond Activation

Influence of the SiO2/Al2O3 molar ratio on the specific properties of NaA zeolite

The aim of this research was to determine the influence of the SiO2/Al2O3 molar ratio on the specific commercial properties of NaA zeolite subtypes as final market products (4A,4A-AG and 4A-MS) under the real production and process conditions. The value of the SiO2/Al2O3 molar ratio, so-called silicate module, was set as independently variable and the effect on the physical and chemical properties of each of the subtypes of NaA zeolites was examined.The paper investigates how the SiO2/Al2O3 molar ratio affects specific properties of NaA powders, namely the ion exchange capacity, oil adsorption capacity and water adsorption capacity. Some previous theoretical and experimental studies have shown that the molar ratio plays a crucial role in the formation of these very similar but for final application different subtypes of NaA zeolite. The experimental part of this work was performed and tested in real production conditions, which can be considered as an advantage in relevance to the obtained results. Various analytical and instrumental testing methods were used for the analysis of the obtained powders, including SEM, XRD and PSD analyses.

Improved charge transfer and morphology on Ti-modified Cu/γ-Al2O3/Al catalyst enhance the activity for methanol steam reforming

The metal-oxide interaction has been considered as an effective factor for catalytic performance in methanol steam reforming. In this work, Ti modified Cu/γ-Al2O3/Al catalyst was prepared by anodization technology. It is found that the addition of Ti can largely increase the surface area of the carrier and thus improve the dispersion of copper. The co-existence of Ti4+ and Ti3+ makes the charge transfer between Cu and Ti easier, which improves the redox performance of copper. The DFT calculations reveal that Ti also enhance the adsorption capacity of water and methanol on the surface of the catalysts. Besides, Ti also reduce the acid density on the carrier, inhibit methanol dehydration reaction and thereby reduce the selectivity of the DME. The optimal catalyst CuTi1.9/γ-Al2O3/Al achieves nearly 100% conversion at 275 °C, while the methanol conversion of Cu/γ-Al2O3/Al is 82%. And the H2 output of CuTi1.9/γ-Al2O3/Al reached 69.17 mol/(kgcat·h) at 300 °C.