Diffusive Pathway Research Articles

Carbon dioxide and methane emissions across tropical and subtropical inland water ecosystems in Brazil: meta-analysis of general patterns and potential drivers

Investigations on CO2 and CH4 emissions from aquatic systems have increased in the last decades, but most studies focus on high-latitude water bodies, with limited information available for tropical and subtropical zones. Here, we compiled CO2 and CH4 emissions by lentic, lotic, and other types of aquatic ecosystems (e.g., floodplains, estuaries, and mangroves) in different biomes in Brazil. We used a literature search of papers published in the last ~ 30 years to analyze reported emission rates, if they were from the diffusive (DF) and/or ebullitive (EB) pathways, and the most used methods. Most studies were carried out in two biomes (Amazon and Atlantic rainforest). The highest emissions were reported in lentic ecosystems (from 0.05 to 4568 mmol CO2 m-2 day-1, and from 0.19 to 348 mmol CH4 m-2 day-1). The DF pathway was more frequently analyzed, and the floating chamber was the most used measurement method. Our analyses indicated the EB pathway can be significant, especially for CH4 in shallow waters. There were many missing data for either DF or EB so we used studies that measured both and system depth to estimate the missing values and then used total emissions (DF+EB) to run predictive models. For the CO2 emissions, pH, water depth, dissolved oxygen, and water temperature were important predictors, whereas the potential drivers for the CH4 emissions were electrical conductivity and the CO2 emissions. More data are necessary to more clearly characterize the drivers of the emissions of such gases, further understand the dynamics of their emissions, as well as refine emission inventories on both regional and global scales in tropical regions.

Efflux and assimilation of xylem-transported CO2 in stems and leaves of tree species with different wood anatomy.

Determining the fate of CO2 respired in woody tissues is necessary to understand plant respiratory physiology and to evaluate CO2 recycling mechanisms. An aqueous 13 C-enriched CO2 solution was infused into the stem of 3-4m tall trees to estimate efflux and assimilation of xylem-transported CO2 via cavity ring-down laser spectroscopy and isotope ratio mass spectrometry, respectively. Different tree locations (lower stem, upper stem and leafy shoots) and tissues (xylem, bark and leaves) were monitored in species with tracheid, diffuse- and ring-porous wood anatomy (cedar, maple and oak, respectively). Radial xylem CO2 diffusivity and xylem [CO2 ] were lower in cedar relative to maple and oak trees, thereby limiting label diffusion. Part of the labeled 13 CO2 was assimilated in cedar (8.7%) and oak (20.6%) trees, mostly in xylem and bark tissues of the stem, while limited solution uptake in maple trees hindered the detection of label assimilation. Little label reached foliar tissues, suggesting substantial label loss along the stem-branch transition following reductions in the radial diffusive pathway. Differences in respiration rates and radial xylem CO2 diffusivity (lower in conifer relative to angiosperm species) might reconcile discrepancies in efflux and assimilation of xylem-transported CO2 so far observed between taxonomic clades.

The inner membrane protein YhdP modulates the rate of anterograde phospholipid flow in Escherichia coli

The outer membrane (OM) of Gram-negative bacteria is a selective permeability barrier that allows uptake of nutrients while simultaneously protecting the cell from harmful compounds. The basic pathways and molecular machinery responsible for transporting lipopolysaccharides (LPS), lipoproteins, and β-barrel proteins to the OM have been identified, but very little is known about phospholipid (PL) transport. To identify genes capable of affecting PL transport, we screened for genetic interactions with mlaA*, a mutant in which anterograde PL transport causes the inner membrane (IM) to shrink and eventually rupture; characterization of mlaA*-mediated lysis suggested that PL transport can occur via a high-flux diffusive flow mechanism. We found that YhdP, an IM protein involved in maintaining the OM permeability barrier, modulates the rate of PL transport during mlaA*-mediated lysis. Deletion of yhdP from mlaA* reduced the rate of IM transport to the OM by 50%, slowing shrinkage of the IM and delaying lysis. As a result, the weakened OM of ∆yhdP cells was further compromised and ruptured before the IM during mlaA*-mediated death. These findings demonstrate the existence of a high-flux diffusive pathway for PL flow in Escherichia coli that is modulated by YhdP.

The net GHG emissions of the Three Gorges Reservoir in China: II. Post-impoundment GHG inventories and full-scale synthesis

Greenhouse gas (GHG) emissions are receiving worldwide attention and concern over the past decades. However, the net change of GHG emissions due to reservoir creation is not well reported. The objective of the study was to evaluate the net GHG emissions of the Three Gorges Reservoir (TGR), the largest reservoir in volume and installed capacity in China. Here, we provide the first full-scale synthesis of GHG emissions in the TGR. Data from two large sampling campaigns between 2010 and 2017 showed that the post-impoundment GHG emissions of the TGR were 1.36 ± 0.16 × 106 tCO2eq yr−1. A majority of GHGs (30%–70%) are emitted from air-water diffusive pathway in the main stem. Anthropogenic carbon and nutrients loads from the reservoir vicinity did not significantly contribute to the post-impoundment GHG emissions. Reservoir GHG emissions were mainly regulated by annual inflow. Subtracting pre-impoundment GHG emissions from post-impoundment emissions, the net GHG emissions of the TGR in our sampling campaigns were 10.41 ± 1.28 × 105 tCO2eq yr−1. In terms of CO2 equivalents per unit of hydropower production in the same years, they were 11.8 ± 1.8 gCO2eq⋅kWh−1. Mass budget analysis showed that flooding and decomposition of organic matter in flooded land could only explain 19.9% of reservoir net GHG emissions. A large proportion of the net GHG emissions needs further study to be quantitatively identified. In addition, our study elaborated the current limitations and further research needs in evaluation of carbon footprints of reservoir creation.

Gelation of the internal core of liposomes as a strategy for stabilization and modified drug delivery II. Theoretical analysis and modelling of in-vitro release experiments.

PEG-DMA was incorporated in unilamellar liposomes. PEG-DMA crosslinking by photo-induced radical reaction transforms the liquid aqueous core of the liposome into a hydrogel. The molecular weight of PEG-DMA significantly influences both structural and release properties of these hybrid nanosystems, by affecting both membrane permeability and diffusional properties of the inner core. Release studies of 5-(6) carboxyfluorescein from Conventional Liposomes (CL) and Gel-in-Liposome (GiL) systems were carried out in a vertical Franz Diffusion Cell. A detailed transport model is proposed, aimed at describing the entire drug diffusive pathway from the vesicles' inner core, through the double-layer membrane, into the buffer solution in the donor chamber of the Franz Cell and from there to the receptor chamber, where withdrawals are performed to evaluate the released drug concentration. The model permits to give a quantitative estimate of the diffusional resistances offered by the inner core (liquid or gelled) and by the double-layer membrane for CLs and different GiLs systems. The theoretical analysis of experimental release data strongly supports the basic assumption that, by varying the molecular weight of PEG-DMA, a different arrangement of the polymer within the liposomal structure and a different interaction with the membrane occur. PEG750-DMA decreases the transport resistance of the double layer membrane with respect to CLs, while PEG4000-DMA plays the opposite role. After gelation of the internal core, the diffusional resistance to drug transport inside GiLs becomes controlling, thus significantly slowing down drug release from these systems. Therefore, the combination of PEG-DMA with phospholipid vesicles appears an interesting strategy to develop sustained drug delivery systems.

Plant root exudates increase methane emissions through direct and indirect pathways

The largest natural source of methane (CH4) to the atmosphere is wetlands, which produce 20% to 50% of total global emissions. Vascular plants play a key role regulating wetland CH4 emissions through multiple mechanisms. They often contain aerenchymatous tissues which act as a diffusive pathway for CH4 to travel from the anoxic soil to the atmosphere and for O2 to diffuse into the soil and enable methanotrophy. Plants also exude carbon from their roots which stimulates microbial activity and fuels methanogenesis. This study investigated these mechanisms in a laboratory experiment utilizing rootboxes containing either Carex aquatilis plants, silicone tubes that simulated aerenchymatous gas transfer, or only soil as a control. CH4 emissions were over 50 times greater from planted boxes than from control boxes or simulated plants, indicating that the physical transport pathway of aerenchyma was of little importance when not paired with other effects of plant biology. Plants were exposed to 13CO2 at two time-points and subsequent enrichment of root tissue, rhizosphere soil, and emitted CH4 was used in an isotope mixing model to determine the proportion of plant-derived versus soil-derived carbon supporting methanogenesis. Results showed that carbon exuded by plants was converted to CH4 but also that planted boxes emitted 28 times more soil-derived carbon than the other experimental treatments. At the end of the experiment, emissions of excess soil-derived carbon from planted boxes exceeded the emission of plant-derived carbon. This result signifies that plants and root exudates altered the soil chemical environment, increased microbial metabolism, and/or changed the microbial community such that microbial utilization of soil carbon was increased (e.g. microbial priming) and/or oxidation of soil-derived CH4 was decreased (e.g., by microbial competition for oxygen).

An automatic smart measurement system with signal decomposition to partition dual-source CO2 flux from maize silage

Carbon dioxide (CO2) is a principal byproduct of various chemical, biological and biochemical processes. CO2 has been measured using various advanced sensors, but a limiting technical challenge has been resolving independent streams of CO2 produced by processes occurring simultaneously. The magnitude and kinetics of each stream may be chemically, biologically or/and physically informative, but such partitioning has received little attention and successful case studies remain rare. In silage production, CO2 flux, an important indicator of aerobic deterioration, microbial activity or oxidative rate of silage, derives from two different pools: gas accumulated in the pores during the early anaerobic phase, and current real-time production of CO2 as oxygenated air enters the silage across the exposed face after opening for feed-out. The former is regarded as a noise confounding the signal and the latter reflects current degradation of the silage. Using a self-developed automatic sensor system with novel signal decomposition, we successfully partitioned CO2 flux into two independent streams derived from the two distinct pools in maize silage, following two independent processes: a physical venting of stored gas through a tortuous diffusive pathway, and a biochemical process generating gas in real time. Three silage samples, treated with a chemical or a biological additive, or left untreated, were tested. The signal decomposition found two best-fit functions (0.8034 ≤ R2 ≤ 0.9036), a quadratic CO2 discharge function and an exponential CO2 production function, for characterizing these distinct processes. These results demonstrate chemical sensor with powerful data-processing capability to resolve the complexity of dual-pool CO2 emission.

Estimation and modeling of pressure-dependent gas diffusion coefficient for coal: A fractal theory-based approach

Diffusion coefficient is one of the key parameters determining the coalbed methane (CBM) reservoir economic viability for exploitation. Diffusion coefficient of coal matrix controls the long-term late production performance for CBM wells as it determines the gas transport effectiveness from matrix to fracture/cleat system. Pore structure directly relates to the gas adsorption and diffusion behaviors, where micropore provides the most abundant adsorption sites and meso- and macro-pore serve as gas diffusive pathway for gas transport. Gas diffusion in coal matrix is usually affected by both Knudsen diffusion and bulk diffusion. A theoretical pore-structure-based model was proposed to estimate the pressure-dependent diffusion coefficient for fractal porous coals. The proposed model dynamically integrates Knudsen and bulk diffusion influxes to define the overall gas transport process. Uniquely, the tortuosity factor derived from the fractal pore model allowed to quantitatively take the pore morphological complexity to define the diffusion for different coals.Both experimental and modeled results suggested that Knudsen diffusion dominated the gas influx at low pressure range (<2.5 MPa) and bulk diffusion dominated at high pressure range (>6 MPa). For intermediate pressure ranges (2.5–6 MPa), combined diffusion should be considered as a weighted sum of Knudsen and bulk diffusion, and the weighing factors directly depended on the Knudsen number. The proposed model was validated against experimental data, where the developed automated computer program based on the Unipore model can automatically and time-effectively estimate the diffusion coefficients with regressing to the pressure-time experimental data. The theoretical determined diffusion coefficients well predicted the pressure-dependent variations of the experimental measured diffusion coefficient for different coals. This theoretical model is the first-of-its-kind to link the realistic complex pore structure into diffusion coefficient based on the fractal theory. The experimental results and proposed model can be coupled into the commercially available simulator to predict the long-term CBM well production profiles.

Two-pore physiologically based pharmacokinetic model with de novo derived parameters for predicting plasma PK of different size protein therapeutics.

Two-pore PBPK models have been used for characterizing the PK of protein therapeutics since 1990s. However, widespread utilization of these models is hampered by the lack of a priori parameter values, which are typically estimated using the observed data. To overcome this hurdle, here we have presented the development of a two-pore PBPK model using de novo derived parameters. The PBPK model was validated using plasma PK data for different size proteins in mice. Using the "two pore theory" we were able to establish the relationship between protein size and key model parameters, such as: permeability-surface area product (PS), vascular reflection coefficient (σ), peclet number (Pe), and glomerular sieving coefficient (θ). The model accounted for size dependent changes in tissue extravasation and glomerular filtration. The model was able to a priori predict the PK of 8 different proteins: IgG (150kDa), scFv-Fc (105kDa), F(ab)2 (100kDa, minibody (80kDa), scFv2 (55kDa), Fab (50kDa), diabody (50kDa), scFv (27kDa), and nanobody (13kDa). In addition, the model was able to provide unprecedented quantitative insight into the relative contribution of convective and diffusive pathway towards trans-capillary mass transportation of different size proteins. The two-pore PBPK model was also able to predict systemic clearance (CL) versus Molecular Weight relationship for different size proteins reasonably well. As such, the PBPK model proposed here represents a bottom-up systems PK model for protein therapeutics, which can serve as a generalized platform for the development of truly translational PBPK model for protein therapeutics.

ATP-Dependent Signaling in Simulations of a Revised Model of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR).

Cystic fibrosis transmembrane conductance regulator (CFTR) is a member of the ATP-binding cassette (ABC) transporter superfamily that has uniquely evolved to function as a chloride channel. It binds and hydrolyzes ATP at its nucleotide binding domains to form a pore providing a diffusive pathway within its transmembrane domains. CFTR is the only known protein from the ABC superfamily with channel activity, and its dysfunction causes the disease cystic fibrosis. While much is known about the functional aspects of CFTR, significant gaps remain, such as the structure-function relationship underlying signaling of ATP binding. In the present work, we refined an existing homology model using an intermediate-resolution (9 Å) published cryo-electron microscopy map. The newly derived models have been simulated in equilibrium molecular dynamics simulations for a total of 2.5 μs in multiple ATP-occupancy states. Putative conformational movements connecting ATP binding with pore formation are elucidated and quantified. Additionally, new interdomain interactions between E543, K968, and K1292 have been identified and confirmed experimentally; these interactions may be relevant for signaling ATP binding and hydrolysis to the transmembrane domains and induction of pore opening.

Boron nitride wash-coated cordierite monolithic catalyst showing high selectivity and productivity for oxidative dehydrogenation of propane

Hexagonal boron nitride (h-BN) is a burgeoning catalyst for oxidative dehydrogenation of propane (ODHP) with impressive light olefins selectivity, which deserves further study to optimize the heat and mass transfer process with the aim of promoting the potential industrial application since ODHP is a highly exothermic process. Herein, h-BN wash-coated cordierite monolithic catalyst was designed through a chemical vapor deposition method using boron acid and urea as precursors, which was used for ODHP reaction and exhibited a ∼16.8% conversion of propane and 82.1% selectivity towards propylene, with only 3.7% selectivity of CO and no detected CO2, at temperature of 535 ℃ and a high gas hourly space velocity (GHSV) of 576,000 mL/gBNh. The typical structure of h-BN/Cordierite with well-developed straight-channel and short diffusive pathway of the thin wash-coated h-BN layer guarantee the mass transfer process at high GHSV, achieving a high propylene space time yield of 18.6 gC3H6 gBN−1 h−1 and improving the selectivity towards propylene and ethylene by suppressing secondary reactions of deep oxidation. Meanwhile, the high GHSV and excellent thermal conductivity of h-BN contribute to the heat transfer during reactions.

Water-induced nanochannel networks in self-assembled block ionomers

Block ionomers cast from solution exhibit solvent-templated morphologies that can be altered by solvent-vapor annealing. When cast from a mixed solvent, a midblock-sulfonated pentablock ionomer self-assembles into spherical ionic microdomains that are loosely connected. Upon exposure to liquid water, nanoscale channels irreversibly develop between the microdomains due to swelling and form a continuous mesoscale network. We use electron tomography and real-time X-ray scattering to follow this transformation and show that the resultant morphology provides a highly effective diffusive pathway.

English

Gas flaring is a recognized polluting agent in the environment, affecting all forms of life. The gases and particulate matters (dust, mist and fog) follow the same diffusive pathway with carbon IV oxide into the plant leaf, where they react with enzymes, hormones, and other biochemical molecules, resulting in the deformation of organelles with adverse consequences. In this study, foliar photomicrography analysis of five medicinal plants (Carica papaya, Chromoleana odorata, Ricinus communis, Manihot esculenta and Euphorbia sp.) from the flare site and non-flare site was used to evaluate the impact of gas flaring in foliar micro-structure. Results showed the occurrence of structural deformities evidenced in distorted veinal arrangement, necrosis, chlorosis, stomata and guard cell destruction. The plants studied have ethno-medicinal and nutritional values in the study area. The study showed that foliar photomicrography could be used as component of vegetation studies in the environmental impact assessment, auditing, and evaluation of any anthropogenic activity. Key words: Gas flaring, phyto-therapeutics, phyto-potency, pollution.

The oxygen supply to thermogenic flowers.

Thermogenic flowers produce heat by intense respiration, and the rates of O2 consumption (Ṁo2) in some species can exceed those of all other tissues of plants and most animals. By exposing intact flowers to a range of O2 pressures (Po2) and measuring Ṁo2, we demonstrate that the highest respiration rates exceed the capacity of the O2 diffusive pathway and become diffusion limited in atmospheric air. The male florets on the inflorescence of Arum concinnatum have the highest known mass-specific Ṁo2 and can be severely diffusion limited. Intact spadices of Japanese skunk cabbage Symplocarpus renifolius are diffusion limited in air only when Ṁo2 is maximal, but not at lower levels. True flowers of the sacred lotus Nelumbo nucifera and the appendix of Arum concinnatum are never diffusion limited in air. Ṁo2 - Po2 curves are evaluated quantitatively with the 'Regulation Index', a new tool to measure dependence of Ṁo2 on ambient Po2 , as well as the conventional 'Critical Po2 '. The study also includes measurements of Po2 within thermogenic tissues with O2-sensitive fibre optics, and reveals that the diffusion pathway is complicated and that O2 can be provided not only from the surface of the tissues but also from the pith of the flower's peduncle.

Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, South East Queensland, Australia

Abstract. Reservoirs have been identified as an important source of non-carbon dioxide (CO2) greenhouse gases with wide ranging fluxes for reported methane (CH4); however, fluxes for nitrous oxide (N2O) are rarely quantified. This study investigates CH4 and N2O sources and emissions in a subtropical freshwater Gold Creek Reservoir, Australia, using a combination of water–air and sediment–water flux measurements and water column and pore water analyses. The reservoir was clearly a source of these gases as surface waters were supersaturated with CH4 and N2O. Atmospheric CH4 fluxes were dominated by ebullition (60 to 99%) relative to diffusive fluxes and ranged from 4.14 × 102 to 3.06 × 105 μmol CH4 m−2 day−1 across the sampling sites. Dissolved CH4 concentrations were highest in the anoxic water column and sediment pore waters (approximately 5 000 000% supersaturated). CH4 production rates of up to 3616 ± 395 μmol CH4 m−2 day−1 were found during sediment incubations in anoxic conditions. These findings are in contrast to N2O where no production was detected during sediment incubations and the highest dissolved N2O concentrations were found in the oxic water column which was 110 to 220% supersaturated with N2O. N2O fluxes to the atmosphere were primarily through the diffusive pathway, mainly driven by diffusive fluxes from the water column and by a minor contribution from sediment diffusion and ebullition. Results suggest that future studies of subtropical reservoirs should monitor CH4 fluxes with an appropriate spatial resolution to ensure capture of ebullition zones, whereas assessment of N2O fluxes should focus on the diffusive pathway.

Two-step nucleation mechanism in solid–solid phase transitions

The microscopic kinetics of ubiquitous solid-solid phase transitions remain poorly understood. Here, by using single-particle-resolution video microscopy of colloidal films of diameter-tunable microspheres, we show that transitions between square and triangular lattices occur via a two-step diffusive nucleation pathway involving liquid nuclei. The nucleation pathway is favoured over the direct one-step nucleation because the energy of the solid/liquid interface is lower than that between solid phases. We also observed that nucleation precursors are particle-swapping loops rather than newly generated structural defects, and that coherent and incoherent facets of the evolving nuclei exhibit different energies and growth rates that can markedly alter the nucleation kinetics. Our findings suggest that an intermediate liquid should exist in the nucleation processes of solid-solid transitions of most metals and alloys, and provide guidance for better control of the kinetics of the transition and for future refinements of solid-solid transition theory.

Simulation of the impact of reversible adsorption on the response time of interdigitated electrode arrays

We simulate the amperometric response time of an interdigitated electrode array with respect to reversible adsorption of redox active molecules at the electrode surface. When neighboring electrodes are biased to potentials below and above the redox potential of the species under investigation, molecules can participate in repetitive reactions leading to an amplification of the Faradaic current. During collisions between molecules and electrodes, the molecules may undergo reversible adsorption. We simulate the behavior of this redox cycling process by using a discrete random walk model, which mimics the diffusive pathway of the molecules. Adsorption probabilities are implemented via the boundary conditions at the electrodes. Using this simulation, we investigate the effect of reversible adsorption on the response time of the interdigitated electrode array.

Evaluation of solute diffusion tortuosity factor models for variously saturated soils

Solute diffusion flux in soil is described by Fick's law along with a tortuosity factor to account for the tortuous and reduced diffusive pathway blocked by soil particles. Predictive models based on empirical or conceptual relationships with other more commonly measured soil attributes have been proposed to replace the time‐consuming and multifarious laboratory measurements. However, these models have not been systematically tested and evaluated with soils of different textures under comparable conditions. This study determined solute diffusion coefficients and calculated tortuosity factors of a sand, a sandy clay loam, and a clay at various degrees of water saturation, and used the experimental data to test the predictive capabilities of these models. All the test models can fit the experimental data reasonably well as evidenced by low root mean square errors (RMSEs). When the proposed (fixed) parameter values were used, the widely accepted Millington and Quirk tortuosity model resulted in highest RMSEs for all three test soils. In terms of model efficiency as described by Akaike weight, however, the tortuosity factors of the sand and sandy clay loam soils are best represented by a quadratic function of volumetric soil water content (with the largest Akaike weights), while the combined parallel‐series conceptual model assuming different configurations of film and pore water is the best for the clay soil. The Olesen power function tortuosity model has the second largest Akaike weights for the sand and sandy clay loam soils, while the So and Nye linear model has the second largest Akaike weight for the clay soil. The two‐region linear model of log (tortuosity factor) versus soil water content uses a similar framework to the conceptual model, and it can satisfactorily fit to the experimental data well (low RMSEs), but with low Akaike weights due to the large number of parameters in the model. Adaption of the findings from this study may substantially improve solute diffusion modeling in unsaturated porous media.

Steady-State Local Diffusive Fluxes in Porous Geo-Materials Obtained by Pore-Scale Simulations

Computer simulations of non-sorbing tracers diffusing in fluid-saturated porous sediment/rock were performed using pore-scale X-ray microtomographic images to reveal the following. (i) The histogram of the magnitude of the local diffusive flux vector obeys a unimodal log-normal distribution having a long positive tail. Simulations using model images were also performed to show that the flux broadening in large pores and the flux mixing at the pore network junctions are responsible for the log-normal shape. (ii) The simulation enabled us to directly visualize pore voxels with large and small fluxes, confirming the existence of transport pores and stagnant pores. Because of the unimodal nature, however, it was difficult to distinguish transport pores from stagnant pores using an objective threshold in the histogram. (iii) Another histogram of the flux vector component along the direction of the macroscopic concentration gradient was analyzed. A negative tail was found in the histogram, indicating that local counter diffusion exists in the porous geo-materials. However, the population and intensity of the counter diffusion fluxes are too small and weak to contribute to the overall diffusive transport across the porous media system. A long positive tail representing a large-flux diffusive pathway was also observed in the histogram. However, again, the population of the large-flux transport pores is small. As a result, the main conveyer of the tracer is the stagnant pores (not the transport pores), which have small positive flux values but a large population.

Hydrogenation of dimethyl oxalate to ethylene glycol on a Cu/SiO2/cordierite monolithic catalyst: Enhanced internal mass transfer and stability

AbstractThe design and application of a Cu/SiO2‐based monolithic catalyst for hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG) is presented. The catalyst was dip‐coated on cordierite with highly dispersed Cu/SiO2 slurry prepared by ammonia evaporation method. This structure guarantees high dispersion of copper species within the mesopores of silica matrix in the form of copper phyllosilicate. The catalyst is low cost, stable, and exhibits high activity in the reaction of hydrogenation of DMO, achieving a 100% conversion of DMO and more than 95% selectivity to EG. Notably, STYEG over the monolith is significantly enhanced compared to the packed bed Cu/SiO2 catalysts in both forms of pellet and cylinder. It is primarily due to the relatively short diffusive pathway of the thin wash‐coat layer and high efficiency of the active phase derived from the monolithic catalyst. Theoretical results indicated that the internal mass transfer is dominated on the catalysts of pellet and cylinders. Moreover, the monolithic catalyst possessed excellent thermal stability compared to the pellet catalyst, which is attributed to the regular channel structure, uniform distribution of flow. © 2011 American Institute of Chemical Engineers AIChE J, 2012