## 4 MWW-Type Materials by Direct Synthesis  
Several efforts have been made to obtain individual zeolitic lamellae separated by direct synthesis, with the main aim of eliminating the swelling and delamination steps. The first MWW-type material with individual lamellae separated from each other was called Direct Synthesis ITQ-2 (DS-ITQ-2). DS-ITQ-2 was obtained by a very similar traditional synthesis of (P)MCM-22 that was modified using \(N\)-hexadecyl-\(N^{\prime}\)-methyl-DABCO (C\({}_{16}\)DC\({}_{1}\)) as a dual template, as shown in Figure 8. DABCO acted as an SDA because of its similarity to HMI, while the tail group (C\({}_{16}\)) avoided the stacking and growth of the structure along the c-axis. The calcined material showed a surface area of 545 m\({}^{2}\cdot\)g\({}^{-1}\) and microporous volume of 0.12 cm\({}^{3}\cdot\)g\({}^{-1}\), which is higher than that of the traditional ITQ-2 (0.08 cm\({}^{3}\cdot\)g\({}^{-1}\)). The pore size distribution showed values in a broad range, which is characteristic of delaminated-type zeolites. MIT-1 was another MWW-type delaminated material obtained by direct synthesis [59]. However, the organic molecule was the TMAda\({}^{+}\)OH\({}^{-}\) linked by alkyl chains with four, five, or six carbons and connected with a CTA\({}^{+}\) molecule, as shown in Figure 8. In this case, the adamantylammonium as the head-group acted as an SDA, the linkers acted to stabilize the pore mouth, and the hydrophobic tail of the CTA\({}^{+}\) molecule prevented zeolitic growth along the c-axis. MIT-1 had a surface area higher than 500 m\({}^{2}\cdot\)g\({}^{-1}\) and a broad distribution of mesopore sizes. Figure 7: Post-synthesis treatment to obtain intracrystalline mesopores in MCM-49 zeolite. TEM micrographs were taken from Reference [58]. Copyright (2015), with permission from Elsevier. Both DS-ITQ-2 and MIT-1 are examples of MWW-type materials obtained when the SDA was linked with a long hydrophobic alkyl chain. Another strategy made use of mixtures of SDA and CTA\({}^{+}\) using a dissolution-recrystallization route to obtain a swollen precursor called Al-ECNU-7P by direct crystallization [60]. The synthesis comprises a dissolution containing MWW seeds (ITQ-1), the 1,3-bis(cyclohex)jimidazolium hydroxide as an SDA, and a silicate source at 140 \({}^{\circ}\)C for 1 h followed by the addition of CTA\({}^{+}\) and the aluminum source. Then, the obtained gel was crystallized at 150 \({}^{\circ}\)C for 72 h, as shown in Figure 9. From the Al-ECNU-7P, it was possible to obtain a pillared material with a basal spacing of 5 nm, a surface area of 701 m\({}^{2}\cdot\)g\({}^{-1}\), and a mesopore size distribution centered at 3.1 nm. The direct calcination of Al-ECNU-7P showed delaminated and partially condensed lamellae, a surface area of 502 m\({}^{2}\cdot\)g\({}^{-1}\), and a mesopore size distribution centered at 5 nm. Figure 8: Representation of the syntheses of DS-ITQ-2 and MIT-1. Figure 9: General scheme of the synthesis of Al-ECNU-7P as well as its pillared and delaminated forms. Another strategy to overcome the diffusional barrier imposed on reactants and products is the synthesis of nanosized zeolites. The decrease of common microsized zeolite crystals to nanosized crystals increases the external surface and could facilitate the rapid diffusion of reactants and products [61]. The synthesis of nanosized MCM-22 zeolite was reported using polydiallydimethylammonium chloride (PDDA) as a protecting or stabilizing agent to avoid the self-aggregation and intergrowth of silica colloids by direct synthesis, as shown in the scheme of Figure 10a. The self-assembly of the cationic polymer and the negatively charged silica species interactions are the main reasons to obtain nanosized MCM-22 with a crystal size of 40 nm, as shown in Figure 10b. Recently, a direct synthesis method was reported to obtain dandelion-like MCM-22 microspheres with interparticle meso/macro voids [63].