Solar Urea: Towards a Sustainable Fertilizer Industry

Abstract

Urea, an agricultural fertilizer, nourishes humanity. The century-old Bosch-Meiser process provides the worlds urea. It is multi-step, consumes enormous amounts of nonrenewable energy, and has a large CO 2 footprint. Thus, developing an eco-friendly synthesis for urea is a priority. Herein we report a single-step Pd/LTA-3A catalyzed synthesis of urea from CO 2 and NH 3 under ambient conditions powered solely by solar energy. Pd nanoparticles serve the dual function of catalyzing the dissociation of NH 3 and providing the photothermal driving force for urea formation, while the absorption capacity of LTA-3A removes by-product H 2 O to shift the equilibrium towards urea production. The solar urea conversion rate from NH 3 and CO 2 is 87 mmol g À1 h À1 . This advance represents a first step towards the use of solar energy in urea production. It provides insights into green fertilizer production, and inspires the vision of sustainable, modular plants for distributed production of urea on farms.Humans and animals excrete excess nitrogen in the form of urea. Historically, urea was the first naturally occurring organic compound to be synthesized by Friedrich Wçhler in 1828. Surprisingly at the time, he made all-organic urea by a thermally induced reconstruction of an all-inorganic compound, ammonium cyanate, connecting the fields of organic and inorganic chemistry.

Tuning the Coordination Structure of CuNC Single Atom Catalysts for Simultaneous Electrochemical Reduction of CO2 and NO3– to Urea

“…[ 4 ] Compared to alternative nitrogenous fertilizers (such as ammonia), urea offers a higher N content, ease and safety of handling, and lower transportation costs. [ 5 ] The vast majority of urea (≈90%) is used as fertilizers ( Figure 1 a), with minor uses including the synthesis of plastics, resins, and adhesives as well as an agent in diesel engines to reduce emissions of nitric oxide. [ 6 ] Crucially, attaining high activity and selectivity toward urea production requires designing effective electrocatalysts with tunable active sites that assist in the adsorption of CO 2 and NO x reactants, to facilitate the electrocatalytic coupling of C and N to form urea.…”

A Reliable and Precise Protocol for Urea Quantification in Photo/Electrocatalysis

“…Photo/ electrocatalytic routes have attracted enormous interest due to their sustainability and cleanliness. [4][5][6][7][8] In 2019, Jiao et al creatively synthesized acetamide via electrocatalytic conversion of carbon monoxide and ammonia, [4] which opened the prelude to the sustainable synthesis of fine chemicals using small molecules (e.g., CO 2 , CO, and N 2 ). Accordingly, the strategies for fixing small molecules into attractive fine chemicals via electrocatalysis have inspired the enthusiastic research on photo/electrocatalytic CN or CC coupling of small molecules to synthesize high-value-added chemicals including urea, [5,6,[9][10][11][12][13][14][15][16][17][18][19][20][21][22] methylamine, [23] glycine, [24] and n-propanol.…”

“…[4][5][6][7][8] In 2019, Jiao et al creatively synthesized acetamide via electrocatalytic conversion of carbon monoxide and ammonia, [4] which opened the prelude to the sustainable synthesis of fine chemicals using small molecules (e.g., CO 2 , CO, and N 2 ). Accordingly, the strategies for fixing small molecules into attractive fine chemicals via electrocatalysis have inspired the enthusiastic research on photo/electrocatalytic CN or CC coupling of small molecules to synthesize high-value-added chemicals including urea, [5,6,[9][10][11][12][13][14][15][16][17][18][19][20][21][22] methylamine, [23] glycine, [24] and n-propanol. [25] Among the above fine chemicals, urea as a substance that kicked off the artificial synthesis of organic matter has been popularly studied through exhaustive experiments, [5,6,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][26][27][28]…”

Accelerated optochemical engineering solutions to CO2 photocatalysis for a sustainable future

“…This process has potential as a sustainable replacement for the Haber-Bosch process as the backbone behind high-output agriculture. 4,5 Operando heterogeneous CO 2 photocatalysis Experiments carried out under operating conditions with real-time detection of reactants, intermediates, and products, referred to as operando, are crucial for obtaining detailed insight into heterogeneously catalyzed CO 2 hydrogenation reactions.…”

“…The interconnectedness and high thermal conductivity of the foam improves the uniformity of the heat distribution and transport to and from the nanostructured photocatalyst while multiple light scattering-reflection events, internally throughout the macroporous structure, increase the probability of light absorption. 5 Enhanced light absorption by the photocatalytic foam has been validated by multiphysics optical modeling of light path tracing, photon residence time, and capture efficiency in a three-dimensional tomographic representation of the foam for different numbers of pores per inch. With the microchannel configuration, the highest quantum efficiencies in the field to date have been recorded, validated by quantitative ferrioxalate actinometry.…”