Customizable Heterogeneous Catalysts: Nonchanneled Advanced Monolithic Supports Manufactured by 3D-Printing for Improved Active Phase Coating Performance

Wood-inspired metamaterial catalyst for robust and high-throughput water purification

Continuous industrialization and other human activities have led to severe water quality deterioration by harmful pollutants. Achieving robust and high-throughput water purification is challenging due to the coupling between mechanical strength, mass transportation and catalytic efficiency. Here, a structure-function integrated system is developed by Douglas fir wood-inspired metamaterial catalysts featuring overlapping microlattices with bimodal pores to decouple the mechanical, transport and catalytic performances. The metamaterial catalyst is prepared by metal 3D printing (316 L stainless steel, mainly Fe) and electrochemically decorated with Co to further boost catalytic functionality. Combining the flexibility of 3D printing and theoretical simulation, the metamaterial catalyst demonstrates a wide range of mechanical-transport-catalysis capabilities while a 70% overlap rate has 3X more strength and surface area per unit volume, and 4X normalized reaction kinetics than those of traditional microlattices. This work demonstrates the rational and harmonious integration of structural and functional design in robust and high throughput water purification, and can inspire the development of various flow catalysts, flow batteries, and functional 3D-printed materials.

Recent Progress and Perspectives of Direct Ink Writing Applications for Mass Transfer Enhancement in Gas-Phase Adsorption and Catalysis

Conventional adsorbents and catalysts shaped by granulation or extrusion have high pressure drop and poor flexibility for chemical, energy, and environmental processes. Direct ink writing (DIW), a kind of 3D printing, has evolved into a crucial technique for manufacturing scalable configurations of adsorbents and catalysts with satisfactory programmable automation, highly optional materials, and reliable construction. Particularly, DIW can generate specific morphologies required for excellent mass transfer kinetics, which is essential in gas-phase adsorption and catalysis. Here, DIW methodologies for mass transfer enhancement in gas-phase adsorption and catalysis, covering the raw materials, fabrication process, auxiliary optimization methods, and practical applications are comprehensively summarized. The prospects and challenges of DIW methodology in realizing good mass transfer kinetics are discussed. Ideal components with a gradient porosity, multi-material structure, and hierarchical morphology are proposed for future investigations.

Review on Additive Manufacturing of Catalysts and Sorbents and the Potential for Process Intensification

Additive manufacturing of catalyst and sorbent materials promises to unlock large design freedom in the structuring of these materials, and could be used to locally tune porosity, shape and resulting parameters throughout the reactor along both the axial and transverse coordinates. This contrasts catalyst structuring by conventional methods, which yields either very dense randomly packed beds or very open cellular structures. Different 3D-printing processes for catalytic and sorbent materials exist, and the selection of an appropriate process, taking into account compatible materials, porosity and resolution, may indeed enable unbounded options for geometries. In this review, recent efforts in the field of 3D-printing of catalyst and sorbent materials are discussed. It will be argued that these efforts, whilst promising, do not yet exploit the full potential of the technology, since most studies considered small structures that are very similar to structures that can be produced through conventional methods. In addition, these studies are mostly motivated by chemical and material considerations within the printing process, without explicitly striving for process intensification. To enable value-added application of 3D-printing in the chemical process industries, three crucial requirements for increased process intensification potential will be set out: i) the production of mechanically stable structures without binders; ii) the introduction of local variations throughout the structure; and iii) the use of multiple materials within one printed structure.

Skeletal Nickel Catalyst for the Methanation Reaction Developed by Laser-Engineered Net-Shaping Technology

Here, we report a skeletal nickel catalyst prepared by cumulative processing. The Ni, Al, and CoCrMo multi-component alloys were printed by a dual-powder laser-engineered net-shaping system, and alloy samples with different components were obtained through high-throughput design. After leaching in 5 mol/L NaOH at 40 °C for 2 h, the specific surface area of the catalyst increased with increasing Al content. Increasing the leaching temperature and prolonging the leaching time also effectively increased the specific surface area of the catalyst. After leaching at 80 °C for 12 h, the specific surface area was 42.36 m2/g. After cleaning and hydrogen-reduction treatment at 400 °C, the catalyst showed high catalytic activity. The highest conversion rate of CO reached 89.56%, and the selectivity of CH4 remained above 98% for a long time.

3D-Printed Fe/γ-Al2O3 Monoliths from MOF-Based Boehmite Inks for the Catalytic Hydroxylation of Phenol

The synthesis of dihydroxybenzenes (DHBZ), essential chemical reagents in numerous industrial processes, with a high degree of selectivity and yield from the hydroxylation of phenol is progressively attracting great interest in the catalysis field. Furthermore, the additive manufacturing of catalysts to produce 3D printed monoliths would provide additional benefits to enhance the DHBZ synthesis performance. Herein, 3D cellular Fe/γ-Al₂O₃ monoliths with a total porosity of 88% and low density (0.43 g·cm^-3) are printed by Robocasting from pseudoplastic Fe-metal-organic frameworks (Fe-MOF)-based aqueous boehmite inks to develop catalytic monoliths containing a Fe network of dispersed clusters (≤5 μm), nanoclusters (<50 nm), and nanoparticles (∼20 nm) into the porous ceramic skeleton. The hydroxylation of phenol in the presence of hydrogen peroxide is carried out at different reaction temperatures (65-85 °C) in a flow reactor filled with eight stacked 3D Fe/γ-Al₂O₃ monoliths and with the following operating conditions: C_phenol,0 = 0.33 M, C_phenol,0/C_H2O2,0 = 1:1 molar, W_R = 2.2 g, and space time (τ = W·Q_L^-1) = 0-147 g_cat·h·L^-1. The scaffolds present a good mechanical resistance (∼1 MPa) to be employed in a catalytic reactor and do not show any cracks or damage after the chemical reaction. DHBZ selectivity (S_DHBZ) of 100% with a yield (Y_DHBZ) of 32% due to the presence of the Fe network in the monoliths is reported at 85 °C, which represents an improved synthesis performance as compared to that obtained by using the conventional Enichem process and the well-known titanium silicalite-1 catalysts (S_DHBZ = 99.1% and Y_DHBZ = 29.6% at 80 °C). This printing strategy allows manufacturing novel 3D structured catalysts for the synthesis of critical chemical compounds with higher reaction efficiencies.

3D printed nickel catalytic static mixers made by corrosive chemical treatment for use in continuous flow hydrogenation

Catalytic static mixers, 3D printed from nickel alloys, were treated with etching or leaching solutions to activate their surfaces for use in hydrogenation of alkenes, aldehydes and nitro-groups.

High Performance Tunable Catalysts Prepared by Using 3D Printing

Honeycomb monoliths are the preferred supports in many industrial heterogeneous catalysis reactions, but current extrusion synthesis only allows obtaining parallel channels. Here, we demonstrate that 3D printing opens new design possibilities that outperform conventional catalysts. High performance carbon integral monoliths have been prepared with a complex network of interconnected channels and have been tested for carbon dioxide hydrogenation to methane after loading a Ni/CeO₂ active phase. CO₂ methanation rate is enhanced by 25% at 300 °C because the novel design forces turbulent flow into the channels network. The methodology and monoliths developed can be applied to other heterogeneous catalysis reactions, and open new synthesis options based on 3D printing to manufacture tailored heterogeneous catalysts.

Current and future trends of additive manufacturing for chemistry applications: a review

Three-dimensional (3-D) printing, also known as additive manufacturing, refers to a method used to generate a physical object by joining materials in a layer-by-layer process from a three-dimensional virtual model. 3-D printing technology has been traditionally employed in rapid prototyping, engineering, and industrial design. More recently, new applications continue to emerge; this is because of its exceptional advantage and flexibility over the traditional manufacturing process. Unlike other conventional manufacturing methods, which are fundamentally subtractive, 3-D printing is additive and, therefore, produces less waste. This review comprehensively summarises the application of additive manufacturing technologies in chemistry, chemical synthesis, and catalysis with particular attention to the production of general laboratory hardware, analytical facilities, reaction devices, and catalytically active substances. It also focuses on new and upcoming applications such as digital chemical synthesis, automation, and robotics in a synthetic environment. While discussing the contribution of this research area in the last decade, the current, future, and economic opportunities of additive manufacturing in chemical research and material development were fully covered.

Recent Advances in 3D Printing of Structured Materials for Adsorption and Catalysis Applications

Porous solids in the form of adsorbents and catalysts play a crucial role in various industrially important chemical, energy, and environmental processes. Formulating them into structured configurations is a key step toward their scale up and successful implementation at the industrial level. Additive manufacturing, also known as 3D printing, has emerged as an invaluable platform for shape engineering porous solids and fabricating scalable configurations for use in a wide variety of separation and reaction applications. However, formulating porous materials into self-standing configurations can dramatically affect their performance and consequently the efficiency of the process wherein they operate. Toward this end, various research groups around the world have investigated the formulation of porous adsorbents and catalysts into structured scaffolds with complex geometries that not only exhibit comparable or improved performance to that of their powder parents but also address the pressure drop and attrition issues of traditional configurations. In this comprehensive review, we summarize the recent advances and current challenges in the field of adsorption and catalysis to better guide the future directions in shape engineering solid materials with a better control on composition, structure, and properties of 3D-printed adsorbents and catalysts.

A Review of the Critical Aspects in the Multi-Scale Modelling of Structured Catalytic Reactors

Structured catalytic reactors are enjoying an increasingly important role in the reaction engineering world. At the same time, there are large and growing efforts to use advanced computational models to describe such reactors. The structured reactor represents a multi-scale problem that is typically modelled at the largest scale only, with sub-models being used to improve the model granularity. Rather than a literature review, this paper provides an overview of the key factors that must be considered when choosing these sub-models (or scale bridges). The example structured reactor selected for illustration purposes is the washcoated honeycomb monolith design. The sub-models reviewed include those for pressure drop, inter- and intra-phase mass and heat transfer, and effective thermal conductivity.