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Recently, carbon dioxide capture and conversion, along with hydrogen from renewable resources, provide an alternative approach to synthesis of useful fuels and chemicals. People are increasingly interested in developing innovative carbon dioxide hydrogenation catalysts, and the pace of progress in this area is accelerating. Accordingly, this perspective presents current state of the art and outlook in synthesis of light olefins, dimethyl ether, liquid fuels, and alcohols through two leading hydrogenation mechanisms: methanol reaction and Fischer-Tropsch based carbon dioxide hydrogenation. The future research directions for developing new heterogeneous catalysts with transformational technologies, including 3D printing and artificial intelligence, are provided. Carbon dioxide (CO 2 ) capture and conversion provide an alternative approach to synthesis of useful fuels and chemicals. Here, Ye et al. give a comprehensive perspective on the current state of the art and outlook of CO 2 catalytic hydrogenation to the synthesis of light olefins, dimethyl ether, liquid fuels, and alcohols.

Catalyst deactivation, the loss over time of catalytic activity and/or selectivity, is a problem of great and continuing concern in the practice of industrial catalytic processes. Costs to industry for catalyst replacement and process shutdown total tens of billions of dollars per year. [...]

This editorial is written to recognize Professor Emeritus Calvin H. Bartholomew, who celebrated his 75th birthday in 2018, and to introduce the commemorative issue of Catalysts compiled in his honor. Following a brief biography that celebrates the career and contributions of Professor Bartholomew, the nine articles that make up the special issue are briefly reviewed. Dr. Bartholomew is an eminent researcher, an outstanding educator, mentor, and friend.

Three large π-conjugated and imine-based COFs, named TFP-TAB, TFP-TTA, and TTA-TTB, were synthesized via the ordered incorporation of benzene and triazine rings in the same host framework to study how the structural units affect the efficiency of CO2 photoreduction. Results from both experiments and density-functional theory (DFT) calculations indicate the separation and transfer of the photoinduced charges is highly related to the triazine-N content and the conjugation degree in the skeletons of COFs. High-efficiency CO2 photoreduction can be achieved by rationally adjusting the number and position of both benzene and triazine rings in the COFs. Specifically, TTA-TTB, with orderly interlaced triazine-benzene heterojunctions, can suppress the recombination probability of electrons and holes, which effectively immobilizes the key species (COOH) and lowers the free energy change of the potential-determining step, and thus exhibits a superior visible-light-induced photocatalytic activity that yields 121.7 μmol HCOOH g−1 h−1. This research, therefore, helps to elucidate the effects of the different structural blocks in COFs on inherent heterogeneous photocatalysis for CO2 reduction at a molecular level. High-efficiency CO2 photoreduction can be achieved by rationally adjusting the number and position of both benzene and triazine rings in covalent organic frameworks (COFs) with orderly interlaced triazine-benzene heterojunctions that can boost their photocatalytic performance. [Display omitted] •Three large π-conjugated and imine-linked COFs employ for efficient visible-light-driven CO2 reduction.•The separation and transfer of the photoinduced charges are highly related to the triazine-N content and the conjugation degree in COFs.•High-efficiency photocatalytic performance can be achieved by rationally engineering benzene and triazine rings in COFs.•COFs with ordered triazine-benzene heterojunctions can suppress the recombination of electron–hole pairs and immobilize the key species.

Globally, coal-fired power plants are the largest industrial source of carbon dioxide (CO2). CO2 emissions from flue gas have potential for direct mineralization with electrostatic precipitator fly ash particles in the field. Demonstration scale accelerated mineral carbonation (AMC) studies were conducted at the Jim Bridger Power Plant, a large coal fired power plant located in Wyoming, USA. AMC produces kinetically rapid conditions for increased rates of mineralization of CO2, sulfur dioxide (SO2) and mercury (Hg) on fly ash particles. Control and AMC reacted fly ash particles were investigated for: change in carbon (expressed as CaCO3), sulfur (expressed as SO42−), and mercury (Hg) contents; topology and surface chemical composition by scanning electron microscope/energy dispersive X-ray spectroscopy analysis; chemical distribution of trace elements; and aqueous mineral solubility by the toxicity characteristic leaching procedure. Results of the AMC process show an increase in C, S, and Hg on AMC fly ash particles suggesting that multiple pollutants from flue gas can be removed through this direct mineral carbonation process. Results also suggest that the AMC process shifts soluble trace elements in fly ash to less leachable mineral fractions. The results of this study can provide insight into potential successful field implementation of AMC.

The extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe3O4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible light using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe2O3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe+2.57 for the catalyst with no lanthana and Fe+2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe+2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe+2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. The paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.

A novel solvent deficient precipitation (SDP) method to produce nanoparticles was studied for its potential in Fischer-Tropsch synthesis (FTS) catalysis. Using Fe(NO3)3·9H2O as the iron-containing precursor, this method produces ferrihydrite particles which are then dried, calcined, reduced, and carbidized to form the active catalytic phase for FTS. Six different drying profiles, including final drying temperatures ranging between 80 and 150°C, were used to investigate the effect of ammonium nitrate (AN), a major by-product of reaction between Fe(NO3)3·9H2O and NH4HCO3 in the SDP method. Since AN has two phase-transitions within this range of drying temperatures, three different AN phases can exist during the drying of the catalyst precursors. These AN phases, along with physical changes occurring during the phase transitions, may affect the pore structure and the agglomeration of ferrihydrite crystallites, suggesting possible reasons for the observed differences in catalytic performance. Catalysts dried at 130°C showed the highest FTS rate and the lowest methane selectivity. In general, better catalytic performance is related to the AN phase present during drying as follows: phase III > phase II > phase I. However, within each AN phase, lower drying temperatures led to better catalytic properties.

Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

Recently, carbon dioxide capture and conversion, along with hydrogen from renewable resources, provide an alternative approach to synthesis of useful fuels and chemicals. People are increasingly interested in developing innovative carbon dioxide hydrogenation catalysts, and the pace of progress in this area is accelerating. Accordingly, this perspective presents current state of the art and outlook in synthesis of light olefins, dimethyl ether, liquid fuels, and alcohols through two leading hydrogenation mechanisms: methanol reaction and Fischer-Tropsch based carbon dioxide hydrogenation. The future research directions for developing new heterogeneous catalysts with transformational technologies, including 3D printing and artificial intelligence, are provided.

ANewAssessmentMethodtoEasilyIdentifyAreasNeedingImprovementinCourse‐levelLearningOutcomesThomas A. Knotts IV, W. Vincent Wilding, William G. Pitt, and Morris D. Argyle Department of Chemical Engineering, Brigham Young University Assessment of student proficiency in expected outcomes, whether on the course or program level, is an important aspect of curriculum development in engineering programs. The reasons for such assessment range from desires to improve student learning to fulfilling requirements of various accreditation bodies. But regardless of the reasons, the challenge is to develop suitable metrics which can clearly identify areas which need improvement. In order to assess student learning, the Department of Chemical Engineering at Brigham Young University has outlined multiple objectives (termed competencies) for each course in the curriculum. Each competency is designed to correspond to a specific program outcome such that assessment of mastery of the course competencies demonstrates achievement of the Program Outcomes. For several years, mastery of the competencies has been measured by direct methods by the faculty and indirectly using surveys by both faculty and students. The student surveys required each pupil to assess his or her mastery of each competency on a scale of 1‐5. Though this approach has provided a numerical evaluation of the abilities of each class as a whole, and has ensured minimum standards are kept, it has proven difficult to glean opportunities for specific improvement from these data, and changes to the curriculum have been largely prompted by the faculty surveys. In an effort to improve the student surveys, changes were recently made to the assessment methods for two courses: Chemical Engineering Thermodynamics and Plant Design. The numerical rating was removed and replaced with a simple yes/no question asking if the student felt proficient in each competency. In addition, the students were asked to select two of the competencies which were given “no” and explain the reason for the weakness. These simple adjustments greatly increased the effectiveness of the student surveys with no additional overhead cost. The data readily identify competencies which are problematic for students and (more importantly) the reasons for the struggles. This facilitates making of precise plans to improve student learning the next time the course is taught. This paper will explain this new assessment process in detail. To illustrate the value of the new procedures, the results of the new method will be compared with those of the traditional method (numerical 1‐5 scale). Emphasis will be placed on showing how the new method not only provides better data, but does so in a time‐efficient manner and makes “closing‐the‐loop” easy. Taken as a whole, the process is such an advancement over the previous method that it instills a sense of excitement for the assessment process that is not usually present in discussions on the topic.