104 results about "Acidum Nicotinicum" patented technology

The invention relates to the technical field of microorganisms, and in particular relates to application of a strain of lactobacillus mucus TG018. The invention further relates to a preparation method of the lactobacillus mucus TG018. The preservation number of the lactobacillus mucus TG018 is CCTCC (China Center for Type Culture Collection) No: M 2023514; the lactobacillus mucus TG018 can be used for producing nicotinic acid, serving as an antioxidant and / or preparing the antioxidant, or can be applied to medicines for reducing uric acid.

The invention relates to the technical field of separation and evaporation of sulfur trioxide, and discloses a device and a process for producing liquid sulfur trioxide by utilizing a film evaporator, the separation of gas-phase sulfur trioxide and low-concentration fuming acid is realized by utilizing the film evaporator, and the liquid sulfur trioxide is separated from the low-concentration fuming acid under the action of gravity and a rotary movable scraper of the film evaporator. Nicotinic acid forms an underspin film on the inner wall of the cylinder wall, and liquid is distributed into a uniform film, so that sulfur trioxide is quickly evaporated, and the evaporation capacity per unit area can be about 6-9 times that of a traditional evaporator; and meanwhile, under the action of high-speed rotating film scraping of the circumference, the heating time is short, the retention time of low-concentration nicotinic acid on the wall surface is shortened, and corrosion of the low-concentration nicotinic acid to the inner wall of the cylinder body at high temperature is avoided. According to the invention, the cyclone is arranged in the film evaporator, so that the material is prevented from being carried by gas, the removal efficiency of fog drops with the particle size of more than 1 micron reaches more than 99.9%, and the evaporation rate can be effectively improved by 1.0-2.6%.

The invention discloses an endogenous anti-aging composition based on an internal and external synergistic mechanism and a preparation method of the endogenous anti-aging composition. The endogenous anti-aging composition based on the internal and external synergistic mechanism is prepared from the following components in parts by mass: 100 to 200 parts of alpha-ketoglutarate calcium; 100 to 200 parts of an olive leaf extract; 10 to 20 parts of nicotinic acid; 10 to 20 parts of pyrroloquinoline quinone; 20 to 60 parts of pomegranate extract; and 10 to 30 parts of coenzyme Q10. The composition and the preparation method thereof have the beneficial effects that the composition capable of integrally improving the aging state of women from multiple dimensions and the preparation method of the composition are provided.

The invention discloses novel dual-emission dissimilar metal MOFs, the chemical formula of which is [Eu2 (na) 6 (CH3OH) 2 (Cu4I4)], and na-is a nicotinic acid radical ion. The MOFs have two secondary structural units: a cubic alkane [Cu4I4] cluster and a 1D inorganic-organic chain [Eu (na) 3] n, each [Cu4I4] cluster serves as a four-connection node, and the 1D [Eu (na) 3] n chain is connected through a nitrogen atom of a na-ligand, so that a three-dimensional skeleton structure is expanded. Tests show that at room temperature, when the compound is excited by 338 nm ultraviolet light, the compound shows two emission centers, a wide emission peak at 557 nm belongs to cluster center triplet emission of a [Cu4I4] cluster, and emission of sharp peaks at 591, 611 and 701 nm corresponds to characteristic emission of Eu < 3 + >. Particularly, the intensity ratio of two fluorescence emission peaks of the compound at 567 nm and 610 nm in the temperature range of 125-300 K and the temperature have a good linear relation, the compound is a sensitive ratio type fluorescence temperature sensing material, and a new thought is provided for application of the ratio type fluorescence temperature sensing material.

The invention relates to the technical field of sulfuric acid production, in particular to a flue gas separation and purification system applied to preparation of electronic-grade sulfuric acid. Comprising a primary treatment tank for removing flue gas impurities, a secondary treatment tank for absorbing sulfur trioxide gas in flue gas, an evaporation tower for evaporating the sulfur trioxide gas from nicotinic acid and a condensation tank for efficiently liquefying the sulfur trioxide gas, impurities and sulfur trioxide gas in flue gas are deeply removed and efficiently enriched through the multi-stage treatment tank in a dual mode of liquid film absorption and spraying absorption, nicotinic acid is subjected to multi-stage evaporation through the preheating cylinder and the evaporation pipe, and separation and purification of the sulfur trioxide gas are achieved in cooperation with the condensation tank and the condensation assembly. And multi-stage condensation treatment combining path extension type pre-condensation, small-strand distributed type secondary condensation and dynamic rotary type comprehensive condensation is carried out, so that an efficient and high-quality condensation purification effect is further achieved.

The invention discloses a construction method of nicotinamide engineering bacteria for cosmetics, which comprises the following steps: amplifying target DNA, recovering the target DNA, carrying out seamless cloning or CPEC connection on the recovered DNA fragment and a vector, carrying out seamless cloning by using a seamless cloning kit of an all-type gold company, carrying out connection by using a sterile ultrapure water complementing system, and carrying out plasmid construction. The method comprises the following steps: inoculating a liquid culture medium with a strain which is verified to be correct, carrying out plasmid extraction on the obtained bacterial liquid by using an AxyPrep plasmid small extraction kit, carrying out shake flask small test on enzyme activity, thallus propagation and protein expression after chassis strain gene editing, adding a substrate 3-cyanopyridine solution into the crushed thallus for reaction, and carrying out HPLC (High Performance Liquid Chromatography) detection on nicotinamide. According to the method, the nitrile hydratase is expressed through metabolism of microorganisms, conversion from 3-cyanopyridine to nicotinamide is achieved through one-step reaction after cell disruption, the enzyme activity of the nitrile hydratase is improved, and meanwhile the generation amount of the by-product nicotinic acid is reduced.

The invention discloses a nicotinic acid immobilized enzyme conversion method, which comprises the following steps: taking wet thalli containing nitrilase, preparing a flocculation clear liquid, passing the flocculation clear liquid through an ultrafiltration membrane, carrying out embedding immobilization to obtain embedded particles not greater than 2mM, and after the embedded particles are hardened, separating and purifying the obtained conversion liquid by adopting a membrane separation method to obtain the nicotinic acid immobilized enzyme. Sequentially carrying out microfiltration, activated carbon decoloration, ultrafiltration, nanofiltration decoloration, acidification crystallization and centrifugation to finally obtain a nicotinic acid finished product. The immobilized enzyme prepared by the method disclosed by the invention can stably exist in nitrile substances, can be repeatedly used for many times, and is high in stability and low in enzyme activity loss rate, and a separated and purified product is free of impurities and high in yield.

The invention discloses a preparation method of mannityl nicotinate impurities, which comprises the following steps: by taking nicotinic acid as an initial raw material, reacting the nicotinic acid with carbonyl diimidazole to generate pyridine-3-carbonyl-imidazole, esterifying with mannitol, and refining and purifying with a mixed solvent to prepare the mannityl nicotinate impurities. The purity of the mannitol nicotinate prepared by the method is not lower than 99%, and the preparation method is simple to operate, simple in post-treatment and suitable for industrial production.

This invention discloses an ultra-low roughness chemical silver plating solution for 6G communication, comprising 2-5 g / L silver nitrate, 10-15 g / L complexing agent, 5-8 g / L nicotinic acid, 2-5 g / L reducing agent, 1-3 g / L stabilizer, 0.1-0.5 g / L surfactant, 10-30 g / L pH adjuster, 0.01-0.1 g / L grain refiner, 0.1-0.5 g / L antioxidant, and water. The invention also provides a method for its preparation. Compared with existing technologies, this invention uses specific halogenated compounds to modify uracil, improving its defects and making it less prone to ionization. The introduced groups also impart crystal plane guiding function, thereby achieving an ultra-low surface roughness of the plating layer.

The invention relates to the technical field of nicotinic acid synthesis, and particularly discloses an efficient nicotinic acid synthesis method based on step-by-step feeding dynamic control, which comprises the following specific steps: step 1, uniformly dividing potassium permanganate into 3 parts, adding the potassium permanganate into an aqueous solution containing 3-methylpyridine every 15 + / -5 minutes, and supplementing 5-8mL of water after each addition; 2, reacting at 70-90 DEG C for 2-4 hours, and filtering while the solution is hot; 3, adding sodium dithionite into the filtrate, wherein the mass of the sodium dithionite is 0.4-0.6 time that of the potassium permanganate; and 4, concentrating the filtrate to 30-50% of the original volume, adjusting the pH value to 3.0-3.5 with acid, and crystallizing to obtain the nicotinic acid. The method has the following effects: the yield is up to 89.52% at most; the cost is reduced: the consumption of hydrochloric acid is reduced by 77%, and the consumption of potassium permanganate is optimized by 16.7%; the efficiency is improved; the reaction time is shortened by 50%; the large fluctuation of the reaction temperature is controlled through step-by-step feeding, the problem that the reaction liquid which is not completely reacted is too alkaline is solved by filtering and adding sodium dithionite, and the false yield is eliminated through the purification and concentration step while the yield is further improved.

The invention discloses a nitrilase mutant and application thereof in nicotinic acid biosynthesis, and belongs to the technical field of enzyme engineering. Through mutation design based on sequence fitness, the nitrilase mutant with improved nitrilase activity, thermal stability and soluble expression level is constructed, and the half-life period of the mutant D1F4 at 50 DEG C can reach 123.40 + / -5.94 min. The high-performance mutant obtained through construction is used for preparing nicotinic acid through whole-cell catalysis of 3-cyanopyridine, the final concentration of the product can be remarkably increased, and the final concentration of the product after 520 min of reaction can reach 2.21 M.

The invention relates to the technical field of microorganisms, in particular to application of lactobacillus rhamnosus TG013 in preparation of an antioxidant product, the preservation number of the lactobacillus rhamnosus TG013 is CCTCC (China Center For Type Culture Collection) NO: M 2023036, and the antioxidant product comprises at least one of pyrroloquinoline quinone, nicotinic acid and an enzymatic antioxidant.

The invention relates to the field of pesticides, and discloses a compound and a preparation method thereof, an intermediate and a preparation method thereof, and a preparation method of 4-trifluoromethyl nicotinic acid, the structural formula of the compound is shown in the specification, and the compound disclosed by the invention is low in preparation cost and easy to separate and purify, and has industrial production potential.

The present invention relates to a strain of Aeromonas salmonicida (Aeromonas salmonicida) HD531 for producing 6-hydroxynicotinic acid through microbial fermentation. The strain belongs to the genus Aeromonas (Aeromomas) of the family Vibrionaceae, and its deposit number at the General Microbiology Center of the China Association for Microbiological Culture Collection is CGMCC No. 7.525. The present invention provides a method for producing 6-hydroxynicotinic acid using nicotinic acid fermentation using the strain. Using a resting cell method, the strain can significantly accumulate 6-hydroxynicotinic acid under aerobic conditions, with a maximum accumulation of 70.16 g / L, at an initial niacin concentration of 10 g / L. The method is suitable for industrial production of 6-hydroxynicotinic acid.

The invention relates to a microbial growth activation accelerant based on rare earth elements as well as a preparation method and application thereof, and belongs to the field of resources and environments. The microbial growth activation accelerant based on the rare earth elements is prepared from the following components: 1 to 150g of a rare earth compound, 0.2 to 2g of pantothenic acid, 0.2 to 2g of nicotinic acid, 0.02 to 0.1 g of nicotinamide and 1000g of deionized water, the rare earth compound is one or combination of more of chlorides of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium, nitric acid compounds and sulfuric acid compounds. A large number of cheap light rare earth elements are used as raw materials of the microbial accelerator, a new utilization approach is provided for the light rare earth elements, the light rare earth elements are converted into high-added-value products, pollution of the light rare earth elements to the environment is reduced, and meanwhile new elements are introduced into the field of microbial accelerators. More importantly, the preparation method of the microbial growth activation accelerant based on the rare earth elements provided by the invention is simple in production process and convenient for large-scale production.

The application discloses a microbial fermentation process for improving coffee fruit acid flavor and belongs to the technical field of coffee processing. The coffee fermentation process is scientific and reasonable to improve the fruit acid flavor of roasted coffee by additionally adding screened strains under the condition of reserving original bacteria of coffee. The fermentation can improve the organic acid content of roasted coffee, wherein the content of citric acid is 8861.58 mu / g, the content of quinic acid is 9291.51 mu / g, the content of maleic acid is 204.32 mu / g, the content of fumaric acid is 190.23 mu / g, the content of succinic acid is 150.69 mu / g, and the content of nicotinic acid is 50.89 mu / g. The coffee fermentation process can improve the coffee bitterness and quality, and the total score of coffee reaches the level of high-quality coffee.

The utility model provides a multi-specification fuming sulfuric acid preparation system. The multi-specification fuming sulfuric acid preparation system comprises a nicotinic acid tower, a first temperature control circulating unit, a second temperature control circulating unit and a cooling unit, a tower plate structure is arranged in a tower cavity of the nicotinic acid tower, and an upper cavity and a lower cavity are formed at the same time. A first absorption unit is arranged in the upper cavity, and a second absorption unit is arranged in the lower cavity. The nicotinic acid tower is provided with an absorption liquid inlet and a feeding hole. The first temperature control circulating unit and the second temperature control circulating unit can collect fuming sulfuric acid formed in the upper cavity and the lower cavity respectively, and the collected fuming sulfuric acid is fed into the corresponding absorption units after being subjected to temperature control. And the cooling unit can circularly feed the gas led out from the tower top to the tower bottom and cool the gas in the circulating process. The multi-specification fuming sulfuric acid preparation system provided by the utility model can ensure that the temperature in the nicotinic acid tower is controlled and adjusted to be proper in the circulating process, so that the preparation effect of fuming sulfuric acid is ensured, and the practicability is high.

The invention discloses a nitrilase mutant and an application technology thereof in synthesis of nicotinic acid, and belongs to the technical fields of gene engineering, enzyme engineering and biological catalysis. The nitrilase mutant disclosed by the invention is obtained by mutating nitrilase from a source of Pseudomonas putida CGMCC (China General Microbiological Culture Collection Center) 3830, and the heterologous expression of the nitrilase mutant in corynebacterium glutamicum is successfully realized. The optimal mutant can efficiently catalyze a substrate 3-cyanopyridine to synthesize 550.68 g / L of nicotinic acid, and the conversion rate is 91.37%.

The invention discloses a tobacco waste comprehensive utilization method based on nicotinamide synthesis and a cigarette, and belongs to the technical field of tobacco waste recycling. The method comprises the following steps: (1) extracting nicotine in the tobacco waste to obtain nicotine and residues, oxidizing the nicotine through potassium permanganate to obtain nicotinic acid, and carrying out nicotinamide reaction on the nicotinic acid to obtain nicotinamide; and (2) treating the residues to obtain a carrier, wherein the carrier can load an adsorbent for flue gas purification. According to the method, potassium permanganate is adopted to oxidize nicotine to obtain nicotinamide, so that the yield of nicotinamide is increased, the harmfulness of nicotinamide preparation is reduced, and the application safety of nicotinamide is further improved; in addition, residues obtained after nicotine is extracted can be prepared into a carrier, after the carrier is loaded with an adsorbent, purification of smoke can be achieved, aroma enhancement of the smoke can be achieved, and therefore comprehensive utilization of tobacco waste is achieved.

The application discloses a nitrile hydratase mutant and application thereof in synthesis of nicotinamide, and belongs to the field of biological catalysis. Am NHase-beta-I106A / K19D / gamma-R8S as a catalyst, 300 g / L of 3-cyanopyridine is converted to obtain 348.5 g / L of nicotinamide under the conditions of 30 DEG C and pH 7.0 for 5 h, while the unmodified nitrile hydratase Am The nitrile hydratase catalyzes generation of nicotinamide to be only 206.3 g / L, and the conversion rate is increased from the original 58.6 % to 99 %. The application further provides a process for preparing immobilized cells from whole cells, which can significantly reduce generation of nicotinic acid byproducts while maintaining high conversion rate, is suitable for industrial amplification production, and provides an excellent enzyme catalyst and process for efficient and green synthesis of nicotinamide.

The invention relates to a composting method for producing high-content nicotinic acid and nicotinamide. The method for preparing the compost comprises the following steps: (1) selecting dry pig manure as a compost raw material; (2) crushing corn straws and tobacco stems into small blocks, and fully mixing the small blocks as a bulking agent with the dry pig manure to obtain a pig manure mixture; and (3) adding a rapid decomposition inoculant into the mixture, and aerating the reactor at the same time to finally prepare the compost with high content of nicotinic acid and nicotinamide. The invention innovatively provides a functional microbial inoculum prepared by adding functional organic wastes and screening dominant strains in a pile body in situ, and the biological fertilizer with personalized nutrients is produced. The research of the invention provides theoretical support for synergistic conversion of multi-element organic wastes, directional screening of microbial agents and preparation of biological fertilizers with personalized nutrients.

The application belongs to the technical field of pharmaceutical chemistry, and provides a high-purity milrinone-nicotinic acid crystal, a preparation method thereof is simple in operation, a crystallization process is easy to control, and reproducibility is good. The prepared milrinone-nicotinic acid crystal has significantly enhanced stability and solubility compared with free base and crystal forms thereof, thereby being beneficial to storage, transportation and application in preparation of a preparation of a product, and having enhanced bioavailability and absorption performance.

The present application relates to smelting flue gas preparation of analytical pure sulfuric acid technical field, disclose a kind of smelting flue gas multistage denitration preparation of analytical pure sulfuric acid system, including primary fine denitration system and secondary purification system, the primary fine denitration system includes ozone generator, drying tower, wherein the ozone generator is arranged at the flue of drying tower inlet smoke port, the secondary purification system includes precision filter and nicotinic acid washing tower, most of NO in flue gas is first oxidized to high-valence nitrogen oxides by ozone, then absorbed by the drying tower circulating acid and denitration, the remaining small amount of NO is catalytically oxidized to high-valence nitrogen oxides by acid preparation conversion process, after secondary filtration and washing purification of precision filter and nicotinic acid washing tower, it enters analytical pure absorption tower, the circulating tank of drying tower and nicotinic acid washing tower is mutually acid, the present application is by " primary fine denitration+two-stage purification " process, the nitrate content in the analytical pure sulfuric acid produced reaches standard.

The present invention relates to a delayed-gelation plugging gel for well cementation, and a preparation method therefor and the use thereof. The delayed-gelation plugging gel for well cementation comprises 2-3 parts of anionic polyacrylamide, 3-4 parts of cationic acrylamide, 1 part of a stabilizer, 1 part of a cross-linking agent, and 6 parts of distilled water, wherein the stabilizer is obtained by reacting citric acid with disodium ethylenediaminetetraacetate under the action of an initiator; and the cross-linking agent is obtained by reacting chromium lactate with chromium nicotinate under the action of azodiisobutylamidine hydrochloride and tetramethylethylenediamine. For the purpose of well cementation, a delayed-gelation plugging gel is provided. The plugging gel is pH-sensitive. By prolonging the gelation time of the gel that originally gelates fast at a certain temperature, a preflush system to which the delayed-gelation plugging gel is added can effectively plug a lost circulation zone when arriving at a destination formation, thereby laying a foundation for the subsequent operation of cement injection.

The invention discloses an amide hydrolase mutant and an application in production of nicotinic acid, and provides two novel amide hydrolase mutants, which can significantly improve the production efficiency and yield of nicotinic acid, reduce the operation steps of nicotinic acid synthesis, realize one-step reaction synthesis from nicotinamide to nicotinic acid after cell disruption, break the bottleneck of the prior art, and improve the production efficiency and yield of nicotinic acid. The synthesis time is greatly shortened while the production cost of the nicotinic acid is reduced, and the production of the nicotinic acid is promoted to develop towards a more efficient, more economic and more environment-friendly direction.

The invention discloses a preparation process of 5-bromonicotinic acid, which comprises the following steps: sequentially adding ethyl nicotinate and pinacol borane into a reaction kettle, heating to react, adding N-bromosuccinimide into the reaction kettle, maintaining the reaction temperature, and filtering to remove a byproduct succinimide after the reaction is finished. And carrying out reduced pressure distillation to recover the solvent to obtain the ethyl 5-bromonicotinate. Adding ethyl 5-bromonicotinate into another reaction kettle, adding an alkali solution, heating, stirring for reaction, cooling reaction liquid after the reaction is finished, dropwise adding hydrochloric acid to adjust the pH value, cooling, crystallizing, filtering, washing a filter cake, and drying to obtain a 5-bromonicotinic acid finished product. The total yield gt of the preparation process of the 5-bromonicotinic acid; the HPLC purity is gt; 99%. The process is simple and convenient to operate and easy to implement, raw materials are cheap and easy to obtain, reaction conditions are mild, high-temperature and high-pressure reaction is not needed, and requirements on equipment are reduced. The whole process is safer to the environment, and green and pollution-free production can be realized.

The invention discloses a preparation method of inositol nicotinate tablets, and belongs to the technical field of pharmaceutical preparations. By optimizing the existing process and coating components, stable dissolution of drugs is realized, and the method comprises the following steps: dispersing inositol nicotinate in mixed oil to prepare an oil phase, mixing and emulsifying the oil phase and a water phase, performing spray drying to obtain drug milk powder, coating the drug milk powder with modified chitosan, and directly tabletting the coated drug milk powder and auxiliary materials. The preparation method comprises the following steps: uniformly dispersing inositol nicotinate in mixed oil to promote the inositol nicotinate to maintain the uniformity of the drug content in the subsequent process, and adsorbing solid particles on the surfaces of drug-containing oil drops through an emulsification technology to protect the drug components; coating components are reasonably designed, so that fixed-point release of the medicine is realized, the medicine is endowed with anti-pressure ability, and the medicine can be directly tableted; and the coated medicine particles are mixed with auxiliary materials and then are directly tableted, so that the process is simplified, and the coating structure of the medicine particles is protected at the same time. The preparation method can prepare the inositol nicotinate tablet with stable drug dissolution, and the inositol nicotinate tablet is good in taste and small in stimulation to gastric mucosa.

The utility model relates to the field of sulfur trioxide production equipment, in particular to a device convenient for evaporation and circulation of fuming sulfuric acid, which comprises a nicotinic acid preheater, a nicotinic acid evaporator, a nicotinic acid circulating pump, a nicotinic acid circulating tank and pipelines for sequentially connecting the devices, the low-concentration smoke acid is fed into the nicotinic acid evaporator, sulfur trioxide gas obtained through evaporation is discharged, the low-concentration smoke acid returns to the nicotinic acid preheater, the nicotinic acid preheater is connected with the nicotinic acid circulating pump, the nicotinic acid circulating pump is connected with the nicotinic acid circulating tank, and the nicotinic acid circulating tank is connected with the nicotinic acid evaporator. Or a pipeline for connecting the nicotinic acid preheater and the nicotinic acid circulating pump is connected with a nicotinic acid circulating tank through a branch pipeline, so that the recycling of the low-concentration flue gas acid is realized, the heat energy consumption of the nicotinic acid preheater is effectively reduced through the subsequent conveying process of the low-concentration flue gas acid, and the low-concentration flue gas acid is conveyed into the nicotinic acid circulating tank for recycling. And the energy consumption management in the conveying process is greatly optimized.

The present invention provides a paliperidone cocrystal, and a preparation method therefor and a use thereof. The cocrystal former of the paliperidone cocrystal is nicotinic acid. The paliperidone cocrystal is obtained by dissolving paliperidone and nicotinic acid in an aqueous organic solvent and then evaporating to dryness under reduced pressure. The paliperidone cocrystal of the present invention has high purity and stable quality, is suitable for commercial storage, has greatly improved solubility and dissolution rate, and is more suitable for the development of paliperidone preparations.

The invention is applicable to the technical field of organic chemistry, and provides a copper-titanium-containing oxygen cluster catalyst and application thereof in synthesis of cyclic carbamate, a preparation method of the copper-titanium-containing oxygen cluster catalyst comprises the following steps: adding ligands into an alcohol solvent, stirring and mixing, the ligands being phenylphosphoric acid, nicotinic acid and triphenylphosphine; adding a copper source, and stirring to uniformly mix; adding a titanium source, and stirring to uniformly mix to obtain a reaction precursor mixture; and placing the sealed reaction precursor mixture in a drying oven for heating reaction to obtain a reaction mixture, cooling the reaction mixture to obtain a yellow crystal, washing, drying, and grinding to obtain yellow powder. The copper-containing titanium oxygen cluster with accurate atoms is prepared in a solvothermal mode and is applied to catalysis of carbon dioxide and propargylamine at normal temperature and normal pressure to directly synthesize the cyclic carbamate compound, copper sites are fully exposed through the copper-containing titanium oxygen cluster with the accurate atoms, meanwhile, adsorption of reactants can be enhanced through coordination of triphenylphosphine, and therefore the cyclic carbamate compound is obtained. The activation energy of the reaction is reduced.